17. An apparatus, comprising: one or more processors, a computer-readable medium coupled to said one or more processors having instructions stored thereon that, when executed by said one or more processors, cause said one or more processors to perform operations comprising: receiving, from a client device operated by a user, a request for a content item; in response to said request, identifying content items available to be sent to said client device; determining one or more designated geographic locations for each of the identified content items; determining one or more contacts of said user, said determined one or more contacts being members of a social network of said user; for each of the identified content items: determining a score for the content item based on a number of tagging actions that were performed by the user's contacts at the determined designated geographic location for the identified content item, wherein said tagging actions mark an association of a person with a particular geographic location; selecting, from the identified content items, a particular content item to be sent to the client device based on the scores; determining that a timestamp associated with at least one of the tagging actions performed at the designated geographic location for the particular content item is within a time period specified by a provider of the particular content item, the timestamp indicating a time of the tagging action; constructing, based on the determination that the timestamp is within the time period, an annotation that identifies at least one of the user's contacts with the tagging action corresponding to the designated geographic location and indicates the time of the tagging action based on the timestamp associated with the at least one location record; and sending said annotation to said client device.
17. An apparatus, comprising: one or more processors, a computer-readable medium coupled to said one or more processors having instructions stored thereon that, when executed by said one or more processors, cause said one or more processors to perform operations comprising: receiving, from a client device operated by a user, a request for a content item; in response to said request, identifying content items available to be sent to said client device; determining one or more designated geographic locations for each of the identified content items; determining one or more contacts of said user, said determined one or more contacts being members of a social network of said user; for each of the identified content items: determining a score for the content item based on a number of tagging actions that were performed by the user's contacts at the determined designated geographic location for the identified content item, wherein said tagging actions mark an association of a person with a particular geographic location; selecting, from the identified content items, a particular content item to be sent to the client device based on the scores; determining that a timestamp associated with at least one of the tagging actions performed at the designated geographic location for the particular content item is within a time period specified by a provider of the particular content item, the timestamp indicating a time of the tagging action; constructing, based on the determination that the timestamp is within the time period, an annotation that identifies at least one of the user's contacts with the tagging action corresponding to the designated geographic location and indicates the time of the tagging action based on the timestamp associated with the at least one location record; and sending said annotation to said client device. 27. The apparatus of claim 17 , wherein said computer-readable medium coupled to said one or more processors has further instructions stored thereon that, when executed by said one or more processors, cause said one or more processors to perform operations further comprising: increasing an ad score for an ad based on a count of location records of the user's contacts associated with said ad from a database; and selecting said ad to be sent to said client device based on said increased ad score.