1. A method performed by one or more computers, the method comprising: receiving, at a server system, data indicating a first user's rating for a content item; storing, by the server system, data that associates the first user's rating with the content item; receiving, by the server system, a search query from a device associated with a second user; and providing, by the server system, search results in response to the search query, the search results indicating the content item and one or more other content items, wherein the search results are selected or ranked based at least in part on the first user's rating for the content item and ratings that other users provided for the content item.
13. The method of claim 1 , wherein the search results comprise multiple search results that each (i) indicate user-provided text associated with a particular content item and (ii) include a link to the particular content item.