Suvey Money Machines is another company that matches you with research companies for free.
When you sign up as a panelist for survey companies, they send you surveys for your demographic (your age, gender, marital status, etc.). You fill out the surveys and then they pay you directly, either by check, PayPal or gift cards (like Amazon or Visa).
Their service is 100% free. They get paid by the research company that provide the survey to you.