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; periodically crawling 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 clustering is performed based at least in part on hyperlinking among the relevant content items; ranking the plurality of clusters against one another, wherein the plurality of clusters are ranked based at least in part on presence of hyperlinking from social network sites to URLs corresponding with the relevant content items; and generating a user interface allowing a user to view and interact with the plurality of clusters.