WackoWiki - WackoWiki is a light and easy to install multilingual Wiki-engine.
Apache JSPWiki - Apache JSPWiki is an open source Wiki engine, feature-rich and built around standard JEE components.
WikkaWiki - WikkaWiki is a flexible, standards-compliant and lightweight wiki engine written in PHP.
JoinDiaspora - JoinDiaspora is a privacy-aware, distributed, open source social network which are open to anyone.
SlimWiki - Beautiful Wikis for Teams. Get started today, free forever!
Hiki - Hiki is a powerful and fast wiki clone written in Ruby.