A While back I joined Mechanical Turk. It is a fun way to spend some time clicking on HITs (Human Intelligence Tasks) and make a little extra cash. Ok, you won't get rich since payments start at $0.01 then increase from there. But you will get paid to your Amazon.com account or you can even ask for it to be transferred to you bank account. It is very simple, just find a Hits that you may be interested in and click to accept. Most task are relatively simple and don't take but a few minutes to complete.
For me, one of the most interesting Hits I have done was back when Steve Fossett's plane went down and Mechanical Turk had it's members searching through satellite photos for his plane. Although it was not found, it still made you feel like you were doing something to help.
If you are looking to make a huge income from Mechanical Turk, well you won't. But you will be able to help people who need feedback from humans and not from a computer.