Dozuki - Dozuki is a web-based tool for creating and distributing step-by-step documentation.
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
DocGen - Static website generator
Dr.Explain - Dr.Explain software is a help file authoring tool.
openSourceCM - Web-based legal document processing and contract management
MadCap Flare - Documentation for Any Audience, Language or Format