5. The method of claim 4 , wherein: a plurality of documents in the set of documents each have a resource locator; grouping the set of documents into a plurality of clusters includes: ordering the set of documents in accordance with the resource locators; and selecting a respective plurality of consecutive documents from the ordering for inclusion in the respective cluster.
5. The method of claim 4 , wherein: a plurality of documents in the set of documents each have a resource locator; grouping the set of documents into a plurality of clusters includes: ordering the set of documents in accordance with the resource locators; and selecting a respective plurality of consecutive documents from the ordering for inclusion in the respective cluster. 6. The method of claim 5 , wherein: the resource locator is a URL; and the respective cluster includes documents from a particular sub-domain within a same domain.