If you are looking to make a few extra dollars here and there, surveys are a good way to do that. I belong to quite a few survey companies, and when I have a little bit of extra time I will do some of the surveys in my inbox. I usually do these while I am watching TV so it is time that I would not have used wisely anyway.
Here are a few of the survey companies I belong to:
Surveyspot - I have belonged to Surveyspot for several years now. I have been paid by them several times. However they do send a lot of invitations, several a day. Check the invitations to see if the survey they are sending you have a points value, because I do get a lot that just say that the incentive is a sweepstakes entry. Surveys are usually 50-200 points, 1 point = 1 cent. I think you can cash out at $10.
MySurvey.com - This has been one of my favorites, although right now they are not taking new sign ups or referrals according to their site. If I see it open up, I'll let you all know! They seem to pay fairly, and I have had opportunities to try some new products using this site!
InboxDollars - This one has some surveys but I usually don't do them because I hadn't qualified. I usually do the pay-per-click email offers that I receive. The cash out threshold is $30, so it takes a while to accumulate this much, but it is nice to get the $30 check when it comes! The good part about this site is that you receive $5 in your account just for signing up! SendEarnings is basically the same type of site as InboxDollars, with the same cash out and $5 sign up bonus.
Surveyhead - I just joined this survey company recently. So far I have not qualified for any surveys I tried to take. They give you $5 to sign up and a few dollars extra if you complete all of the profiles. You only need $10 to cash out and I think you can only cash out for magazine subscriptions (It's ok for me, I love magazines!). I'm not sure how this one will go yet.
There are many more, but these are just a few I belong to. I will be posting more in the future! If you have a question about any survey sites, please let me know, because I have tried many of them!