Experts Exchange!

Stack Exchange is a fast-growing network of 84 [and counting] question and answer sites on diverse topics from software programming to cooking to photography and gaming. We are an expert knowledge exchange: a place where physics researchers can ask each other about quantum entanglement, computer programmers can ask about JavaScript date formats, and photographers can share knowledge about taking great pictures in the snow.

Super User, part of Stack Exchange , is a Q&A site for computer enthusiasts that's free. Free to ask questions, free to answer questions, free to read, free to index, built with plain old HTML, no fake rot13 text on the home page, no scammy google-cloaking tactics, no salespeople, no JavaScript windows dropping down in front of the answer asking for $12.95 to go away. You can register if you want to collect karma and win valuable flair that will appear next to your name, but otherwise, it's just free. And fast. Very, very fast. »

Server Fault is a Q&A site for system administrators and IT professionals that's free. Free to ask questions, free to answer questions, free to read, free to index, built with plain old HTML, no fake rot13 text on the home page, no scammy google-cloaking tactics, no salespeople, no JavaScript windows dropping down in front of the answer asking for $12.95 to go away. You can register if you want to collect karma and win valuable flair that will appear next to your name, but otherwise, it's just free. And fast. Very, very fast. »

Shapado is a questions and answers site for your enterprise or community, your “knowledge base on the cloud”. It makes sure questions never get asked twice by making the information flow.

Scoold is inspired by StackOverflow and implements most of its features. You can ask and answer questions, upvote and downvote posts, earn badges and reputation. Each edit creates an new revision, making it easy to follow the history of edits. Scoold is optimized for the cloud. You can simply click the 'Deploy to Heroku' button and get up-and-running in minutes. You can deploy it to your favorite PaaS, too.

AllAnswered.com allows any community to create question and answer boards for any topics that they are interested in. It is absolutely free to use no matter how big or small your community is. AllAnswered.com strives to be the place where people can get their questions answered and build a strong community by helping each other.

Use Shrtct to prepare your team, make important decisions, gather and store information, plan, debate and hash it out. Everywhere and anytime.

BitAsker is a paid question and answer plateform using Bitcoin ... a user can win money by answering a question.