19. The system of claim 16 , where the one or more instructions for selecting the representative comprises: one or more instructions for selecting the representative for each of the one or more clusters based on a measure of quality associated with each of the documents.
16. A system, comprising: at least one computer-readable medium containing computer-executable instructions, the at least one computer-readable medium comprising: one or more instructions for clustering documents into one or more clusters in a current clustering process; one or more instructions for selecting a representative for each of the one or more clusters; one or more instructions for determining if the representative has been re-crawled since a prior clustering process; one or more instructions for determining a previous representative associated with the representative in the prior clustering process, if it is determined that the representative has not been re-crawled; one or more instructions for forming a combined cluster that includes one of the one or more clusters associated with the representative that has not been re-crawled and one of the one or more clusters to which the previous representative has been assigned in the current clustering process; and one or more instructions for storing information related to the combined cluster.