With reference to surveillance studies theory, this paper critically assesses the role of personalized search engines as a mediator between advertisers and users. It first sketches the economic and technical background of online marketing and personalized searches. Then, it engages in an in-depth discussion of two examples of personalized search engines with regard to the data collection process used and the way in which this data is used for advertising purposes. The discussion shows that users' information needs, as well as their personal data, are subject to a growing pressure in terms of commercial exploitation. Essentially, search engines now fulfill the task of translating information needs into consumption needs.