Citizendium Save
Wiki with stricter editing rules and obligatory disclosure of editor's real names.
http://www.citizendium.org/   

Connected: An Internet Encyclopedia Save
The engineering, theoretical concepts, and organizations of the Internet (freely distributable).
http://www.freesoft.org/CIE/   

Cunnan Save
An encyclopedia for reenactors of the Middle Ages and Renaissance period with a heavy slant towards members of the Society for Creative Anachronism.
http://cunnan.sca.org.au   

Everything2 Save
An extensively hyperlinked collection of facts, ideas, notes and humor to which anyone can add.
http://www.everything2.com/   

Memory Alpha Save
A peer edited Star Trek encyclopedia.
http://memory-alpha.org   

Musipedia Save
A collaborative music encyclopedia. Contains melodies and musical themes from classical, popular, and folk music. Can be searched based on the melody alone, either by playing it on a keyboard, whistling or singing, or by entering the melodic contour as Parsons Code.
http://www.musipedia.org   

Open Site Save
A volunteer-run open content encyclopedia.
http://open-site.org/   

PlanetMath Save
Collaborative, peer-reviewed mathematics encyclopedia with TeX input, inspired by MathWorld (GNU Free Documentation License).
http://planetmath.org/   

Plastics Wiki Save
Wiki-based website dedicated to plastics technology, polymer materials, equipment and other things related to polymers and plastics.
http://plastics.inwiki.org/   

SourceWatch Save
A directory of people, organizations and issues shaping the public agenda. It catalogs PR firms, activist groups and government agencies as well as the criticisms that are made of these groups from different perspectives.
http://www.sourcewatch.org/   

Technomanifestos Network Save
Collaborative resource on the history of computing and the Internet (GNU Free Documentation License), and the online companion to the book Technomanifestos.
http://www.technomanifestos.net   

Wikipedia Article - Nupedia Save
Nupedia was a public peer-reviewed general encyclopedia created by volunteer scholars, with resources for readers and contributors (GNU Free Documentation License). It can be considered to be Wikipedia's direct ancestor.
http://en.wikipedia.org/wiki/Nupedia   

dKosopedia Save
A collaborative project of the DailyKos community to build a political encyclopedia.
http://www.dkosopedia.com/   

Help build the largest human-edited directory of the web
Suggest a site | Open Directory Project | Become an editor