Have you ever heard about PaidStudies.net? Well, we hadn't either until a few days ago because they just started up.
Paid studies is a recent start-up website that has been in the planning for several years. Here's a quote from their site if you want to know more.
And here is a little more about how it works:
So we, Paid Studies, act as a middleman between the Huge researchers and the individual consumers!
Don't expect to find tons of studies yet, as they are still new.
Visit their site here at Paid Studies