Ok, not every 'paid' survey site is created equal. I HATE Valued Opinions, I am about to opt out today. THey have you fill out the survey like 75% through and then ONE question can mess you up. I spent 20 minutes on a survey that was offering a good reward, and after saying that I hadn't heard of a certain computer program, they said that I didn't qualify for the survey!! I was like, what a rip off! Seriously, VO, pay your people! I should know if I qualify within the first 2 minutes of doing a survey. Such a waste!
On the other hand, there is my favorites- Mysurvey.com and Opinion Outpost http://opinionoutpost.com/join/8762726
These offer generous points and their surveys are actually enjoyable! I will tell you that they don't offer that many surveys, but when they do, it's usually worth it. Mysurvey has super short surveys, but it takes a while to accumulate enought points to do something, but I would say the same for OO.
Well, survey sites aren't going to get you rich, but if you have free time they can be fairly lucrative. :)