askalo - In May 2017, askalo was relaunched as a free classifieds search engine for cars, jobs and real...
AskBot - Askbot enables users to create Q&A forums.
Wiki Answers - Answers.com: Wiki Q&A combined with free online dictionary, thesaurus, and encyclopedias.
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
Quora - Quora is a place to gain and share knowledge. It's a platform to ask questions and connect with people who contribute unique insights and quality answers.
OSQA - OSQA is the free, open source Q&A system you've been waiting for.