Abstract: This specification describes technologies relating to displaying online content. In general, one aspect of the subject matter described in this specification can be embodied in methods that include receiving a collection of advertisement candidates for display in an online medium, the advertisement candidates each assigned a quality score calculated based at least in part on a measure indicative of relevance of the respective advertisement candidate to online content for concurrent display in the online medium, determining a score threshold based at least in part on relationships among multiple quality scores of the quality scores associated with the advertisement candidates in the collection of advertisement candidates, and based on the determined score threshold, identifying a subset of advertisement candidates of the collection for display. Other embodiments of this aspect include corresponding systems, apparatus, and computer program products.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for facilitating online conversation. In one aspect, a method includes determining that a user has submitted a question to be viewed by trusted participants of an online conversation, wherein the trusted participants include the user, one or more advertisers and one or more social network friends of the user, obtaining a reply to the question from one of the trusted participants, and providing the reply to the trusted participants.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for facilitating online conversation. In one aspect, a method includes obtaining a search query; identifying, by a search engine, resources that are responsive to the search query, wherein the resources include information that references an online conversation in which a user has submitted questions to be viewed by trusted participants and one or more of the trusted participants has replied to the question, and wherein the trusted participants include the user, one or more advertisers and one or more social network friends of the user; and providing information that identifies the resources for display.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for facilitating online conversation. In one aspect, a method includes determining that a user has submitted a question to be viewed by trusted participants of an online conversation, wherein the trusted participants include the user, one or more advertisers and one or more social network friends of the user, obtaining a reply to the question from one of the trusted participants, and providing the reply to the trusted participants.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for facilitating online conversation. In one aspect, a method includes determining that a user has submitted a question to be viewed by trusted participants of an online conversation, wherein the trusted participants include the user, one or more advertisers and one or more social network friends of the user, obtaining a reply to the question from one of the trusted participants, and providing the reply to the trusted participants.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for facilitating online conversation. In one aspect, a method includes determining that a user has submitted a question to be viewed by trusted participants of an online conversation, wherein the trusted participants include the user, one or more advertisers and one or more social network friends of the user, obtaining a reply to the question from one of the trusted participants, and providing the reply to the trusted participants.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for facilitating online conversation. In one aspect, a method includes determining that a user has submitted a question to be viewed by trusted participants of an online conversation, wherein the trusted participants include the user, one or more advertisers and one or more social network friends of the user, obtaining a reply to the question from one of the trusted participants, and providing the reply to the trusted participants.