Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.

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.