16. The method of claim 11 , wherein: the network-based commerce system includes a plurality of registration sites; the user is registered with the network-based commerce system as corresponding to a registration site among the plurality of registration sites; and the determining that the set of listings each satisfy the criterion includes determining that each listing of the set of listings is available to the user based on the registration site that corresponds to the user.
11. The method of claim 1 , wherein: the identifying of the recommended listing includes: determining that the set of listings each satisfy a criterion; ranking each listing of the set of listings; and selecting the recommended listing from the set of ranked listings.