6. The one or more computer storage media of claim 1 , wherein clustering the relevant content items into the plurality of clusters is further based at least in part on ad hoc clustering in which text of the relevant content items is analyzed to identify relationships among the relevant content items.
1. One or more computer storage media storing computer-useable instructions that, when used by one or more computing devices, cause the one or more computing devices to perform a method comprising: receiving an initial set of search queries including one or more input search queries, the one or more input search queries having been manually determined to be relevant to a given subject area; generating an expanded set of search queries by analyzing search engine session data to identify a plurality of additional search queries related to the one or more input search queries, the expanded set of search queries including the one or more input search queries and the plurality of additional search queries; employing the expanded set of search queries to identify a plurality of URLs relevant to the given subject area, each URL in the plurality of URLs associated with a website, wherein employing the expanded set of search queries to identify the plurality of URLs relevant to the given subject area comprises analyzing search engine session data and user web browsing data based on the expanded set of search queries to identify the plurality of URLs; determining for each URL in the plurality of URLs a section of the website that is relevant to the given subject area; periodically crawling, based on the section identified for each URL, documents associated with the plurality of URLs, to provide a plurality of content items from the URLs; employing a classifier to identify relevant content items from the plurality of content items, the relevant content items being determined by the classifier to be relevant to the given subject area; clustering the relevant content items into a plurality of clusters, each cluster including a group of content items associated with a particular event or topic within the given subject area, wherein the particular event or topic is associated with a main content item identified based on the number of hyperlinks in the relevant content items to the main content item; ranking the plurality of clusters against one another, wherein ranking comprises: (1) retrieving content from social network sites; (2) counting within the content from social network sites the number of hyperlinks to URLs corresponding with the relevant content items within the plurality of clusters; and (3) ranking a first cluster higher than a second cluster when the first cluster has more hyperlinks than the second cluster; and generating a user interface allowing a user to view and interact with the plurality of clusters, wherein the user interface provides, for each cluster, the main content item and a plurality of related content items, wherein the plurality of related content items comprises the content from social network sites having hyperlinks to URLs corresponding with the relevant content items.