A thread named Dmoz "mini Directories'" Everywhere at HighRankings Forum discusses an old classic issue for the search engines. The Open Directory Project, DMOZ.org, clones. ODP provides a method for one to automatically create and update their clones at the Open Directory RDF Dump. You can either download a piece or whole of the directory.
So how many of these are out there? Some in the thread guess about 4,000. DMOZ lists about 360. But everyone knows that is not accurate.