Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
DigitalChalk - Online Training Software and Learning Management System (LMS)
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
Workplace by Facebook - Connect everyone in your company and turn ideas into action.
Askalot - Askalot is a next generation CQA (Community Question and Answer) system.
Moxtra - Moxtra is a multi layered, embeddable team collaboration solution.