WikiMatrix
- A tool to compare the features of various popular wiki engines in comfortable side-by-side tables.
- http://www.wikimatrix.org/

coWiki
- A content management tool with an intuitive markup language, unixlike access management, a directory structure and seamless page renaming.
- http://www.cowiki.org/

GeboGebo - Wiki system
- GeboGebo is an open source wiki system based on tdbengine. It is small, easy to set up and administrate and stores all data in a local, indexed database. It can optionally hold all content as static html pages, too.
- http://www.gebogebo.org

TiddlyWiki
- An experimental microcontent WikiWikiWeb built by Jeremy Ruston. It's written in HTML and JavaScript to run on any browser without needing any serverside logic. It allows anyone to create self-contained hypertext documents that can be posted to any web se
- http://www.tiddlywiki.com/

WikiWeb, Inc.
- Commercial Windows-based implementation written in Smalltalk with limits on allowed named users, Access support, and ODBC support with more expensive versions.
- http://www.wikiweb.com/

Wiki Engines
- Links to dozens of Wiki system types, in many programming languages.
- http://c2.com/cgi-bin/wiki?WikiEngines

Vanilla
- An extensible wiki engine written in REBOL, with weblog features and a streamlined interface.
- http://www.vanillasite.at/

SushiWiki
- A wiki-like Web application running on .NET platforms. It is written in C#, uses ASP.NET features and stores data in SQL databases or flat XML files.
- http://sourceforge.net/projects/sushiwiki

Platypus Wiki
- A Semantic WikiWikiWeb that uses RDF to manage metadata and ontologies.
- http://platypuswiki.sourceforge.net/

Perspective
- Open Source wiki engine, written in C#/XSLT, that supports WYSIWYG editing, file attachments, searching across pages and attachments (including MS Office documents) and a flexible security model.
- http://www.high-beyond.com/

OpenWiki
- An IIS/ASP implementation with strong XML support.
- http://openwiki.com/

FlexWiki
- A wiki implementation that uses Microsoft's .NET technology (C# and ASP.NET) and has support for wiki namespaces.
- http://www.flexwiki.com/