Free Wiki

Note: Although better described as a Content Management System (CMS), TikiWiki is included here because of its wiki capability.

From the TikiWiki Site:

"Tiki CMS/Groupware (aka TikiWiki) is a powerful open-source Content Management System (CMS) and Groupware that can be used to create all sorts of Web applications, Sites, Portals, Intranets and Extranets. TikiWiki also works great as a Web-based collaboration tool. TikiWiki is a multi-purpose package with a lot of native options and sections that you can enable/disable as you need them. It is designed to be international, clean and extensible.

TikiWiki incorporates all the features present in several excellent wiki systems available today plus a lot of new features and options, allowing your wiki application to be whatever you want it to be--from a simple wiki to a complex site for a whole user community with many intermediate steps. You can use TikiWiki as a forums site, a chatroom, for poll taking, and much more! The possibilities are endless.

TikiWiki's major features include: article, forum, newsletter, blog, file/image gallery, wiki, drawing, tracker, directory, poll/survey, quiz, FAQ, chat, banner, webmail, calendar, category, ACL, and more."

Features:

Full TikiWiki Feature List

User Screenshot:

Admin Screenshot:

Demo Link:

TikiWiki Demo

Documentation:

TikiWiki Documentation

System Requirements:

TikiWiki System Requirements

Helpful Resources:

TikiWiki Developer Site
TikiWiki Sourceforge Page
TikiWiki Freshmeat Listing

Download:

http://tikiwiki.org/Download

License:

GNU Lesser General Public License (LGPL)