MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
DigitalChalk - Online Training Software and Learning Management System (LMS)
Tiki Wiki CMS Groupware - Tiki Wiki CMS Groupware, also known as Tiki (or TikiWiki), is a full-featured, web-based, multilingual, all-in-one Free/Libre Open Source Software solution. Tiki can be used to create all kinds of web apps, portals, knowledge bases, intranets, etc.
Workplace by Facebook - Connect everyone in your company and turn ideas into action.
DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Onehub - Onehub helps businesses securely share and control files in the cloud.