17. One or more non-transitory machine-readable media storing instructions which, when executed by one or more processors, cause: receiving a request to provide a set of one or more advertisements to be displayed on a particular webpage; in response to receiving the request, causing the set of advertisements to be displayed on said particular webpage; and causing, to be displayed on said particular webpage, a value for each advertisement in the set, wherein said value is selected from a group consisting of: a link count indicating a number of links from a plurality of linking webpages that each links to an advertisement webpage corresponding to said each advertisement; a tag count indicating a number of tags that have been associated with said advertisement webpage by a plurality of users who have visited said advertisement webpage, wherein each tag of said tags is (a) one or more words and (b) created, by a user of the plurality of users to describe content of said advertisement webpage, subsequent to the creation of said advertisement webpage; and a trust rank that a web crawler, which is associated with an entity that receives the request, associates with said advertisement webpage, wherein the trust rank is based, at least in part, on user-created tags that describe content of said advertisement webpage and that have been associated with said advertisement webpage subsequent to the creation of said advertisement webpage.
19. The one or more non-transitory machine-readable media of claim 17 , wherein: causing said value for each advertisement in the set to be displayed includes causing a clickable item to be displayed on said particular webpage; and the instructions, when executed by the one or more processors, further cause: receiving an indication that the clickable item has been selected; and in response to the indication, providing a new page that contains at least one of (a) Uniform Resource Locators (URLs) of a subset of said plurality of linking webpages or (b) a subset of said tags.