Abstract: A method for selection of items for one or more users includes performing each of a set of steps to determine the items. Performing the steps includes introducing a controlled variation into a result of each of multiple of the steps. The items for the one or more users are then selected according to the results of the steps.

Abstract: A method for recommending items includes forming one or more choice sets of recommendable items. At least one choice set is a personalized choice set of recommendable items formed for a first user based in part on data associated with that user. Recommendable items can be divided into classification groups. Forming a choice set of recommendable items can be based on a user's classification group preferences. The method also includes forming a recommendation set of recommendable items from the choice sets of recommendable items. Forming the recommendation set is based in part on additional data associated with the user. The additional data is not used in forming the personalized choice set.

Abstract: Systems and methods for recommending items to users include maintaining a database of user-related information including user profiles, each including at least a history of user activities associated with a first entity that has a relationship with an inventory of recommendable items; obtaining information about an identity of a user interacting with a second entity different from the first entity and different from the service provider; associating the identity of the user interacting with the second entity with a corresponding user profile; selecting a first set of items from the inventory for presentation to the user based at least on an analysis of a history of user activities associated with the first entity; and forming a specification of the selected first set items for presentation to the user during the user's interaction with the second entity.

Abstract: A system examines a user profile based on a knowledge associated with a user. The system examines a content context profile associated with a type of application and an application environment. The system examines an advertisement profile associated with a plurality of advertisements that include a plurality of attributes. The system then conditionally selects at least one preferred advertisement from the plurality of advertisements for presentation to the user. The at least one preferred advertisement is selected based on a statistical analysis of the user profile, the advertisement profile, and the content context profile.