Open-Site

Description
"Open-Site.org, a free, trusted, online ."

Potential editors must submit "an original paragraph (or more) of at least 25 words so that we may evaluate your writing capabilities." before being allowed to edit the site.

All text is available under the terms of the GNU Free Documentation License.

Open-Site uses a custom "Open-Site Code 2.0"  (although some argue that it is "a CMS, not a wiki") that is available for download under the GPL.