Bloomfire - Let Bloomfire help you get organized! Organize your content, build your company knowledge base and help your employees to be more successful.
MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
Confluence - Confluence is content collaboration software that changes how modern teams work
Ema Personal Wiki - Ema Personal Wiki uses Markdown to freely create and manage structured notes, like a website.
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
Pmwiki - PmWiki is a wiki-based system for collaborative creation and maintenance of websites.