I've been working with Toluna for well over a year now and don't have any complaints! I've cashed out four times with them, all last year, since I haven't really been doing surveys this year so far. I gotta get back into it, and start making some more money.
Anyway, Toluna is a free site that pays you to take surveys that they send to your email. They won't overload your inbox, so no worries there.
You'll receive 500 points just for signing up with Toluna. Then 600 points for each of the Personal Interest Surveys on your profile page. When you complete all of them, you'll also receive a 2,000 point bonus!!! And then of course you get points for each of the regular surveys you complete.
Sign up for Toluna here and start making some extra cash!
I've just added Toluna to my list of good survey sites. You can find that list here. Also, find the list anytime by clicking the PAID SURVEYS tab on the toolbar above.