1. A user-interface method of selecting and presenting a collection of content items in which the presentation is ordered at least in part based on inferring preferences of a given user from a plurality of users of an input device, the preferences of the plurality of users of the input device being learned based on content items selected by the plurality of users, the method comprising: providing a set of content items, each content item having at least one associated descriptive term to describe the content item; receiving incremental inputs from a shared input device; in response to said incremental input, presenting a corresponding subset of content items; receiving from the shared input device selection actions of content items; analyzing the descriptive terms associated with the selected content items to learn a composite set of preferred descriptive terms of the plurality of users of the shared input device, wherein the shared input device used by the plurality of users is a solitary input device used by each user of the plurality of users so that the composite set of preferred descriptive terms collectively describes the descriptive terms associated with content items selected by each of the users of the plurality; inferring preferences of individual users of the plurality of users of the shared input device from the composite set of preferred descriptive terms by decomposing the composite set of preferred descriptive terms into individual sets of preferred descriptive terms, said decomposition act utilizing prespecified statistical models of preferences of a population according to demographic information; subsequent to learning the composite set of preferred descriptive terms of the plurality of users, receiving at least one content item selection action from one of the individual users and selecting an individual set of preferred descriptive terms for use in subsequent content item selections based on comparing said at least one selected content item to the individual sets of preferred descriptive terms; in response to receiving subsequent incremental input from the shared input device, selecting and ordering a collection of content items based on the individual set of preferred descriptive terms selected for use in subsequent content item selections; and presenting the ordered collection of content items on a display device.