Valued Opinions – Decent site with reasonable surveys ($2 for a 20 min survey). Everyone is annoyed by this site because they tacked on a $2 few to the Amazon $20 gift card and $5 to the $20 Visa gift card so it costs $22 to get the $20 Amazon and $25 to get the $20 Visa. They claim its because of extra fees they incur. I dunno. Also, it can take weeks to get credited for a survey which is frustrating.
Some pay with points that are redeemable for cash or goods and typically you must rack up a bunch to redeem them for anything of significance. Others may give you a gift card, discount, or another token of appreciation for participating. Many others pay nothing or only offer sweepstakes entries for completing screening surveys to determine your eligibility for other, paid surveys. A few don't pay much of anything, unless you recruit others, as in a pyramid scheme.
I also have used Synovate Global Opinion Panels, which is now I-Say by Ipsos. They send you surveys pretty frequently and the points you accumulate can turn into actual money! You can receive an actual check from them, or choose to redeem for a gift card. I haven’t cashed out with them since they changed into the new system, just because I’ve really stopped taking the surveys because I’m lazy 🙂 Here’s the link: http://i-say.com/Rewards/RewardsProgram/tabid/203/language/en-US/Default.aspx
IOCS is a not-for-profit research organization that conducts studies and experiments on shopping-related behavior – things like how we, as consumers, evaluate products, how we make the buying decisions, etc. Although the focus is mostly on shopping related behavior, some of their experiments and studies include broader areas of marketing, psychology, and economics.