The non-profit Wikimedia Foundation is the parent organization of Wikipedia, Wiktionary, Wikiquote, Wikibooks, Wikisource, In Memoriam 9/11 and Nupedia. Its goals are to maintain and develop open content, wiki-based projects and to provide the full contents of those projects to the public free of charge.
Official site: http://wikimediafoundation.org/
Contact information including local chapters is available there.
This category has the following 6 subcategories, out of 6 total.