The Free / Libre / Open Source Web App with the most built-in features
WackoWiki is a light and easy to install multilingual Wiki-engine.
The Free & Popular MediaWiki Web Software in Complete Virtual Machine
stro is an open-source cross-platform MMORPG server.
Cavendish-MW is a MediaWiki skin based on Mozilla's Cavendish skin
Simplest wiki+tracker system
The Halo extension extends MediaWiki and Semantic Mediawiki
MediaWiki extension to create flowcharts from the links between pages.
Small and Simple Wiki