OpinionPaycheck.com has put together a database of nearly 400 Marketing Research companies who will pay you to fill out surveys & participate in focus groups. New companies get added to their database frequently.

What makes them different from other survey sites? They manually check out EVERY company in the directory and rate them between 1-10 for customer service and payout! They do this by sending out an email to each company and seeing how they respond to questions and concerns. They ask them about survey availability and also how much they have paid to members. They also received feedback from current members and included this information in the ratings system. Having rated these companies 1-10, they exclude any companies who did not score at least a six, thus offering only quality highly recommended companies.

After registering, free of charge, with Survey Saanvi you will have the opportunity to sign up with up to 50 online paid survey companies that ready to pay you for your opinion. Their Paid Survey Guide shows you, step-by-step, how to take advantage of one of the easiest ways to put extra cash in your pocket month after month for rest of your life.

Not only is SurveyClub completely free, but they've recently undertaken a huge project to establish:

• The quality and quantity of surveys
• The average "reward" or payment
• Their respect of consumers' privacy

Their research was extensive - they registered at 432 websites available to residents of USA and Canada, took hundreds of surveys, looked for signs of privacy abuse, and literally analyzed every company from start to finish.

It took over 260 hours, but when the dust settled and they crunched the numbers they finally had the answers you wanted and the Top 25 are revealed on the site. In their experience, you'll make more money with these companies, than all the rest combined!

If you're a resident of USA or Canada, visit them here

If you're looking for quantity, YellowSurveys.com is a free listing of over 500 survey sites worldwide. Obviously with a listing this large, a few links are obsolete, or incorrectly identified as international rather than US only, but overall, a very impressive site.

Another comprehensive site is Free Paid Surveys. Not only do they list around 300 sites, by region, but they are also give category listings for such topics as music, sport and technology, together with a list of sites that offer bonuses for referring friends and family.