Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for receiving an identifier associated with a user of a social networking service, identifying one or more first services provided by a first service provider, determining that the user is a user of the one or more first services based on the identifier, identifying first contacts of the user within each of the one or more first services, and generating a social vicinity index based on the first contacts, the social vicinity index including one or more potential contacts for the user within the social networking service.

Abstract: In one embodiment, a method for a detection server in communication with each of multiple web pages of multiple websites on multiple web servers, the detection server in communication with an ad indexing server, includes automatically accessing from the detection server a file for rendering the web page from a web server, automatically building an object model of the web page at the detection server using the accessed file, automatically scanning the object model at the detection server for one or more elements that are advertisements, automatically analyzing each scanned advertisement at the detection server to determine one or more attributes of the scanned advertisement, and automatically storing data at the ad indexing server on the determined attributes of the scanned advertisements found at the detection server to facilitate an indexing of advertisements on the web pages of the websites.