46. The medium according to claim 39 , wherein the description of online activities includes a description of whether the user made a purchase on the Web site.
39. A machine-readable medium storing instructions adapted to be executed by a processor to: receive a description of online activities for a collection of online identities for users accessing one or more affiliate web sites; identify a desired behavior, the desired behavior describing user interaction that indicates that an online identity demonstrating the desired behavior is more likely to be responsive to a re-targeted advertisement; analyze the description of online activities to determine whether a particular online identity appearing in the description of the online activities demonstrates the desired behavior; generate a watch list of users to receive advertisements based on analyzing the description of online activities; monitor, in real-time and from the one or more affiliate web sites, information related to user interaction with the one or more affiliate web sites; receive a request to display advertising content to a user; determine that the user appears in the watch list of users to receive re-targeted advertisements; and select, in response to the request, advertising content for display based upon determining that the user appears in the watch list of users to receive re-targeted advertisements.