A system analyzes a user's historic browsing activity to determine one or more topics of interest to the user and displays to the user one or more advertisements that are relevant to the user's topic(s) of interest. The system analyzes a plurality of browses to determine the user's interest(s). Each...http://www.google.ca/patents/US20050033771?utm_source=gb-gplus-sharePatent US20050033771 - Contextual advertising system
