1. A computer-implemented method of allowing access to content on an unknown device in a format appropriate for that device, comprising: under control of one or more computer systems configured with executable instructions, receiving a request from a user to access identified content on an electronic device, the electronic device not previously being associated with the user; requesting secure user identification information from the user, the secure user identification information including a secure private key entered into the electronic device by the user; in response to receiving the secure user identification information, validating the secure user identification information and determining rights for the user with respect to the identified content; requesting capability information for the electronic device, from the electronic device; determining an amount of bandwidth available for a usage plan associated with the user; in response to receiving capability information for the electronic device, determining at least one format of at least a portion of the identified content to be accessible via the electronic device based on the capability information, the rights for the user with respect to the identified content, the amount of bandwidth available for the usage plan, and an amount of currently used bandwidth; and allowing the user to access the identified content in the determined at least one format on the electronic device.