Embodiments of the present invention allow a user to replace unwanted content, such as advertisements, in data distributed over a network with wanted content. Data include Web pages, Internet television broadcasts, Internet radio broadcasts, or any other kind of data that contains content. The data, such as a Web page, is ultimately presented on the user's system, presenting the user with the wanted content. Wanted content includes, among other things, personal photographs, advertisements that the user has expressed interest in, and even advertisements for which the user is compensated for viewing or listening to. In accordance with the present invention, a user opts in to a system that replaces unwanted content with wanted content. The user opts in by providing information that helps determine (a) what content he does not want to see and thus will likely ignore if presented to him and (b) what content he would likely find interesting and thus likely view. This information includes URLs for Web sites; personal information, such as age, income, hobbies, and vacation plans; and work information, such as salary and job title.