Survey sites are free to join and will pay you for surveys you take.
They are online divisions of market research companies.
Especially if you are from US or Canada, you can expect to get a lot of surveys depending on your profile. But you have to answer the survey invites before they expire or reach the expected number of respondents.
Yes, they do pay you. Some of friends have got made hunderds of dollars, but I haven't managed that much. It all depends on your profiles, what the survey companies or market research firms want.
You can get a few more details here:
http://getpaidtosearch.Blargh!!...33;/survey.html