fig1 illustrates a content selection and delivery system 100 according to an aspect of the present invention . the system 100 comprises a central server 102 , including a processor 104 , memory 106 , storage 108 , and network interface 110 , communicating over a bus 112 . the server 102 stores a content repository 114 , including a library of audio and video titles , for example . for simplicity a single server 102 is illustrated here , with the content repository 114 residing on the server 102 , but it will be recognized that the functions described here may be distributed across data processing equipment as desired . for example , if the system 100 is large , multiple servers may be employed , and if the data repository 114 stores a large number of titles , the repository 114 may be distributed across numerous data storage devices . further , while audio and video content are described as examples , it will be recognized that other content may be stored in addition or as an alternative thereto , such as digital books , games , or other software . the server 102 communicates with one or more user terminals through a network 116 , which may suitably provide access to the public internet 118 . the system 100 supports a number of terminals , of which examples presented here include a point of sale kiosk 120 , a user &# 39 ; s personal computer 122 , a user &# 39 ; s personal device 124 , and a user &# 39 ; s media center device 126 . the various terminals may suitably communicate with the server 102 through the internet 118 . the server 102 maintains a user account manager 128 , suitably implemented as software residing in storage 108 and transferred to memory 106 as needed for execution by the processor 108 . the user account manager 128 creates and maintains a plurality of user accounts stored as user records in a user account database 130 . each user account record includes identification information for the user , as well as a set of user preferences for the types of content preferred both overall and for particular purposes , as well as a history of each content item received and a user rating for each content item , if the user has provided a rating . the user account record for a user also includes identification information for the devices used to communicate with the server 102 , allowing convenient identification of a user through the association between a user and an identified device , and also allowing for the evaluation of trends or preferences on a device by device basis if desired . the server 102 further maintains a transaction manager 132 for managing user transactions for receiving content , and a communication manager 134 for receiving communications from a terminal and responding to the communications as appropriate . when a user initiates contact through a terminal , the communication manager 134 attempts to identify the device and the user associated with the device . if the communication manager 134 cannot identify the device , it presents an interface inviting the user to enter account information or to choose to open an account . if the communication manager 134 identifies the device , or if the user enters account information , the communication manager 134 invokes the transaction manager 132 , supplying the transaction manager 132 with the user account information associated with the user record for the user . if the user chooses to open an account , the communication manager 134 invokes the account manager 128 , which presents an interface allowing the user to enter personal information , to enter information identifying the various user devices that may be used to play content and to present such devices as the user may have readily available in order to allow the account manager 128 to read identifying information from the devices , such as electronic serial numbers , internet protocol ( ip ) addresses , stored computer identification indicia , and the like . once the user has submitted the desired identification information , the account manager 128 presents one or more interfaces allowing the user to submit preferences , including types of video and music preferred by the user , the types of activities or events for which the user may wish accompaniment , the durations of the activities or events , and the preferences of the user with respect to such activities or events . for example , a user may specify different types of exercise activities , such as yoga or aerobics , and may specify a preference for melodious , soothing music for yoga and music with a rapid , distinct beat for aerobics . the account manger 128 may be invoked not only at the initiation of a user account , but at any time desired by the user or , as appropriate , by the transaction manager 132 . the transaction manager 132 provides the account manager 128 with information identifying each content item delivered to the user , and the packaging of the content item . content items will frequently be delivered as packages appropriate to a user &# 39 ; s activities , such as collections of video , collections of songs , playlists of songs already on the user &# 39 ; s device , or collections of songs and video , and the transaction manger 132 provides the account manager 128 with information identifying the contents of each such package delivered to a user . the account manager 128 updates the user &# 39 ; s account record in order to improve the ability to make selections for the user . in addition , the account manager 128 may also receive rating information provided by the user . when a user opens a new transaction , updates account information , or responds positively to a request to provide information about the user &# 39 ; s experience , the user may supply user ratings of content items and packages , including both the overall user evaluation of the item or package and its suitability to the activity with which it was used . the account manager 128 updates the user &# 39 ; s account record with rating information provided by the user , and this rating information may be used to enhance selections . the account manager 128 further presents selections allowing the user to enter payment preferences . for example , a user may enter financial information , such as a credit or debit card number to avoid the need to enter the information during transactions , and may enter preferences relating to the acceptance of advertising with the content . one mechanism for distributing content to users is to include advertising with the content and collect payment from advertisers , thereby reducing or eliminating the financial cost to the user , and a user may choose to receive advertising for some or all content with which advertising is offered , or may choose to receive advertising for content delivered in association with particular activities . such choices and preferences are stored in the user account record , but these choices and preferences may be changed by the user at any time . in addition , the user may use any desired payment mechanism , or accept or reject advertising , at the time of a transaction , with any previously stored preferences being used as defaults that may be changed as desired in a particular transaction . the transaction manager 132 provides the account manager 128 with information relating to changes from previously stored preferences , or entry of selections with respect to payment and advertising when no previous preferences exist , and the account manager 128 which may use information relating to such changes and entries of selections to modify or create stored preferences for the user . once a user has established an account , the user may invoke the transaction manager 132 if desired , or may simply close the session . when invoked , the transaction manager 132 presents an interface to the user allowing the user to make entries indicating the type and duration of activities or events for which content is needed , and to provide any other information needed to assemble an appropriate package of content . in order to simplify the selection process for the user as much as possible , selections are made based on the activity and the duration and on the user preferences with respect thereto , rather than requiring a user to select specific items and build them into a package . therefore , the initial interface is relatively simple and need not present the names of specific items for selection . however , options may be made available that will invoke further interfaces allowing a user to select specific titles in order to build his or her own package . if a user does build his or her own package , details of the package are provided to the account manager 128 , and the package may be used as a model for subsequent packages assembled for the same or a similar purpose . if desired , the user may enter additional details of the activity . for example , if the activity is an airplane flight , the user may indicate whether electric power will be available during the flight . playing of video during a long flight may exceed the battery capacity of most personal video players , so that a package for such a flight would typically consist primarily of audio . however , if electric power is available to the user during the flight , battery capacity is less of an issue and more video can be included in the package if the normal user preferences so indicate . once the user has finished making entries , the transaction manager 132 invokes a package assembly module 136 , delivering the user preferences and selections to the package assembly module 136 . the package assembly module 136 examines the user preferences and selections and assembles an appropriate package based on the user preferences and selections . the package assembly module defines the duration of the package based on factors such as the nature and expected duration of the activity as well as explicit user specification , if any , and balances audio and video based on the nature of the activity and user preferences related to various activities and overall user preferences . for example , a user may specify an overall preference for video over audio , but the package assembly module 136 will nevertheless select audio in cases in which video would be inappropriate , such as walking or running outdoors or for exercise such as weightlifting , which requires relatively short periods of activity and frequent changes of activity . on the other hand , a user who expresses an overall preference for audio may receive an all audio package for relatively short rides on public transportation , but may receive a package in which the audio is mixed in with video on longer rides , such as intercontinental airplane flights in which the availability of only one type of content may lead to boredom with that type of content . once the duration of the package and the balance of the content has been determined , the package assembly module 136 examines the data repository 114 to select content items for the package . content items are based on such user preferences as are available , such as type of music , audiobook or other spoken word such as poetry or comedy , video genre such as comedy , drama , classic movies , television , and the like . content , especially video content , may also be chosen in part by duration to fill expected periods of an activity . for example , on a late night transcontinental flight , a 30 minute comedy may fill the period between the time when passengers are allowed to use their portable devices and the beginning of dinner , and a 90 minute movie may fill the period between the conclusion of breakfast and landing at the destination . once the content comprising the package has been identified , the package assembly module 136 invokes the transaction manager 132 , which presents a list of the content items and their types and genres for approval , together with a price of each item , an overall price , and the choice , if available , to receive advertising in full or partial payment . once the user has provided approval and the transaction is concluded , the content items comprising the package are retrieved from the repository 114 and made available for delivery to a user device . in one exemplary implementation , each content item is delivered individually , along with a playlist that can be selected by the user in order to play the items in sequence . if desired , in accordance with user preferences and to simplify the experience for the user , explicit approval and payment need not be performed . instead , the package may simply be compiled and delivered with payment being conducted on terms previously chosen by the user . in addition , rather than selecting and delivering content , the package assembly module 136 may simply compile a playlist that may be used to select a playback sequence for content already stored on a user &# 39 ; s device , such as content previously received from the system 100 or content received from other sources , with a listing of contents of the user &# 39 ; s device having been previously stored in the user &# 39 ; s account record . if desired , for user devices that support digital rights management ( drm ) to allow playback of content only under specified circumstances , the user may choose to download content without being required to pay for it immediately . when playback is desired , the user may submit or authorize payment and receive digital rights management information needed to allow playback . such a procedure allows a user to download or transfer content , which typically requires longer download or transfer times , at a convenient time . when the user decides to pay for the content and wishes to receive digital rights management information , the digital rights management information can typically be downloaded or transferred much more quickly than can the actual content . alternatively or in addition , the use of drm information may be used to deliver content subject to restricted conditions so that the content may be made available at a lower cost . for example , content may be subject to drm restrictions allowing for a playback only during a limited time , such as two weeks from delivery . fig2 illustrates a process 200 according to an aspect of the present invention . the process 200 may suitably be implemented using a system such as the system 100 of fig1 . at step 200 , a repository of titles is assembled . at step 202 , upon initiation of contact by a user , a device used to initiate contact is examined to determine if it can be identified . if the device can be identified , the process proceeds to step 203 and the user associated with the device is identified . the process then skips to step 210 . if the device cannot be identified , the process skips to step 204 and an interface is presented to the user allowing the user to enter identifying information or choose to open an account . if the user enters identifying information , the process skips to step 210 . if the user chooses to open an account , the process proceeds to step 206 and an initial account information interface is presented , allowing entry of user identification information and information such as payment information , content preference information , both overall and with respect to various categories of activities , identifying information for user devices and device preference information identifying the various devices that may be used for different activities . once the user has entered all the information desired , the process proceeds to step 208 and a user record is created for the user and a user identifier is assigned to the user . the user may then choose to conclude the session , in which case the process terminates at step 250 , or to conduct further activities , in which case the process proceeds to step 210 . at step 210 , the user account record associated with the user is retrieved . at step 212 , the user is presented with an interface allowing the user to change preferences and provide relevant information , such as ratings of content items previously delivered , anticipated upcoming activities , changes in types of activities commonly engaged in , and the like . upon a user indication that assembly of a content package is desired , the process proceeds to step 214 and an interface is presented allowing the user to make entries and selections indicating preferences relating to the content package . upon indication by the user that indication of preferences is complete , the process proceeds to step 216 and content items are identified to form a package . at step 218 , a list of the identified content items is presented to the user for approval , and at step 220 , an interface is presented allowing the user to conduct a transaction , selecting payment methods and providing payment details , which may include acceptance of advertising . at step 222 , the content items making up the package are assembled and made available to the user , such as by download to the user &# 39 ; s computer , by transfer to the user &# 39 ; s personal device at a kiosk , by delivery to a user &# 39 ; s removable media device , or by wireless transfer to a user &# 39 ; s data device . if desired , content may be protected using digital rights management ( drm ) information and delivered , with the rights assigned by the drm information depending on the nature of the payment transaction , such as a lower price for a limited time availability or a free or nominal transfer , permitting later authorization of playback upon a subsequent payment transaction and delivery of drm information authorizing playback . at step 224 , the user record for the user is updated with details of the user preferences and selections and the identities of the content items comprising the package . at step 250 , the process concludes . while the present invention is disclosed in the context of a presently preferred embodiment , it will be recognized that a wide variety of implementations may be employed by persons of ordinary skill in the art consistent with the above discussion and the claims which follow below .