Amazon started a new question & answer service called Askville. To assure a high quality answers in each topic Askville gives "experience points to users based on how good their answers are in a particular topic."
All the services on Askville are free and if your answers are great you will also be awarded with quest coins that could be used in the upcoming 2007 Amazon's website called Questville.com.
One of the most inetersting Q & A services that I found lately is AskMetaFilter created by Matt Haughey and moderated Jessamyn West from Librarian.net. With a few simple rules AskMetafilter has created a very dedicated online community able to answer a lot of difficult questions.
A detailed post from Anil Dash provides more inside info on AskMetaFilter.
Via: Librarian In Black