1. A computer-implemented method comprising: forming, using a choice set module, one or more choice sets of recommendable items, including forming for a first user at least one personalized choice set of recommendable items based in part on first data associated with the first user, wherein the recommendable items are divided into classification groups and the first data includes the first user's classification group preferences, and forming the at least one personalized choice set of recommendable items is based on the first user's classification group preferences; and forming, using a recommendation set module, a recommendation set of recommendable items, including selecting one or more of the recommendable items included in the one or more choice sets of recommendable items, where forming the recommendation set is based in part on second data associated with the first user, the second data not used in forming the personalized choice set.