Wikimedia Public Data Dumps
http://meta.wikimedia.org/wiki/Data_dumps

Wikimedia provides public dumps of their wikis’ content: 1) for archival/backup purposes; 2) for offline use; 3) for academic research; 4) for republishing (don’t forget to follow the license terms); 5) for fun!; and 6) The timezone of the file dates is UTC. This has been added to the tools section of Research Resources Subject Tracer™ Information Blog. This will be added to the Web Data Extractors white paper. This has been added to Business Intelligence Resources Subject Tracer™ Information Blog.