Question and answer sites are fun to spend time and it is also an effective way to start your internet business. Some of the popular Q and A sites are ehow.com and answers.com
How about launching your own Q&A site for free? I don't know how to monetize it but if ou are technicall sound, then I suppose you can do it.
Go to qhub.com to create your own free Q&A site with just a few clicks. I just tried it but it got stuck just before the final step.
Here it is my site's URL: justask.qhub.com
But it will be a nice exposure creating custom Q&A site.