StackOverflow

2leep Clone Script

OpenMind

http://openmind.sourceforge.net/default.html
Free
http://i.imgur.com/lFskwL4.png
2leep Clone Script

Qwench is a PHP/mySQL based StackOverflow clone. Features: Allow users to post questions and answers, points system similar to StackOverflow, ability to post an article as a knowledge-base (for corporates), ability to lock site to registered users only, clean CSS layout, works in all major browsers. Requirements: PHP 4+ and mySQL.

http://anantgarg.com/2009/12/09/php-stackoverflow-clone/
Free
http://i.imgur.com/lFskwL4.png
2leep Clone Script

Create an amazing Questions and Answers, responsive website with ScriptFolder- Questions and Answers. It has been designed with latest technology and gathering features from Yahoo! Answers, Ask, Quora, answerbag etc. ScriptFolder- Questions and Answers created SEO friendly, user-friendly and it is light weight to make your sever run smooth and index your site in search engines faster. User friendly admin panel offers you full privilege to manage your site and install take only 10minutes

http://www.scriptfolder.com/products/
Free
http://i.imgur.com/lFskwL4.png
2leep Clone Script

Shapado is another Stack Overflow-like app written in Ruby on Rails, mongomapper and mongodb. Using this script you can make a Stack Overflow Clone or a Yahoo Answers Clone

http://gitorious.org/shapado#more
Free
http://i.imgur.com/lFskwL4.png
2leep Clone Script

SOClone will make use of Progressive Enhancement to ensure that all core functionality is available regardless of whether or not the user has JavaScript enabled – some of Stack Overflow’s core functionality such as voting, accepting answers, viewing comments, marking questions as favourites and flagging questions as offensive currently doesn’t work at all without JavaScript enabled. Another usability issue which will be fixed is that the lack of submit buttons on some search pages means they can’t be used in browsers whose input method does not support typing events, such as Opera on the Nintendo Wii.

http://code.google.com/p/soclone/
Free
http://i.imgur.com/lFskwL4.png