I participate in several survey research companies on-line for extra money. No, you're not going to become an overnight millionaire when you participate in these programs, but I have easily made a couple hundred dollars over the last several months by doing surveys here and there! Here are the ones I recommend:
Toluna (I just got a $40 check from them!) This one is by invite only so click on the link and enter your e-mail and I will send you an invite.