1. A method of improving the way a computer provides personalized advertising to users of internet web pages, the method comprising the steps of: a) providing an index server maintaining dynamic indices to internet web pages and employing a hierarchical plurality of topic categories whose contents are maintained and updated by the index server, wherein a master index is maintained as well as one for each user; b) permitting a user to customize the user's index by addition of an internet web page to the user's index in conjunction with one or more topic categories; c) permitting the user to customize the user's index by deleting, renaming, and re-hierarchializing topic categories and to specify any subset of the plurality of topic categories as customized by the user; d) performing customization value calculations to determine numeric customization values, each of the numeric customization values representing how much the user has customized a respective one of the topic categories; e) calculating a numeric interest value for at least some of the topic categories, wherein calculating a numeric interest value for at least some of the topic categories comprises using the numeric customization values for a respective one of the topic categories; f) at request of the user, executing a search of the index server in any category of the subset but only of categories in the subset; and g) serving to the user an advertisement based at least in part upon the calculated numeric interest value.