StackOverFlow.com is one the best question and answer website that is like a drug for everyone who is looking for some plain no-nonsense answers. So, what if you want to host similar question and answer website? Do you develop your own? Sure why not. But, if you do not want to develop you own but to have one that workes like StackOverFlow.com, there are few options…
Lampcms is an full-featured Open Source Question and Answers web program with deep integration with Facebook, Twitter, Tumblr and Blogger and soon LinkedIn APIs. Click here for more.
An open source StackOverFlow clone. Click here for more and download.
An Open Source implementation of a similar system to StackOverFlow. Get it here.
Also, visit Stack Exchange to find more questions and answers websites.