The relevance of advertisements to a user's interests is improved. In one implementation, the content of a web page is analyzed to determine a list of one or more topics associated with that web page. An advertisement is considered to be relevant to that web page if it is associated with keywords belonging to the list of one or more topics

ontent stream analysis is a user profiling technique that generates a user profile based on the content files selected and viewed by a user. This user profile can then used to help select an advertisement or other media presentation to be shown to the user.

There is disclosed a server and local device that interface for selecting advertisements to be viewed by users of an online service based upon user activity. The local device preferably maintains a targeted activity list of activity identifiers and associated advertisements. The local device monitors the activity on the local device and compares the activity to the identifiers in the targeted activity list. If the activity matches one of the identifiers, the local device plays one or more advertisements.

The computer system capable of associating related advertisements to individual search results items uses the following subsystems: 1) a product database; 2) a user/session manager; 3) a product matching manager; 4) a product listing manager; and, 5) a result presentation manager.