MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
Bloomfire - Let Bloomfire help you get organized! Organize your content, build your company knowledge base and help your employees to be more successful.
Pmwiki - PmWiki is a wiki-based system for collaborative creation and maintenance of websites.
Confluence - Confluence is content collaboration software that changes how modern teams work
PukiWiki - PukiWiki is a functional and reliable wiki software that has been widely using for Japanese wikis and is using the PHP framework.
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.