Another great paid survey panel is Datatelligence. Not only do they conduct regular online surveys, but they also host many high-paying focus groups and at-home product tests. I haven't had any experience with their product tests, but the focus groups I have participated in with them were very simple and not too time-consuming. One of them only lasted a week and took between 5-15 minutes a day. It paid over $20 for what ended up being less than an hour of work! They send email invitations for these and other surveys fairly frequently and I've had a lot of luck qualifying for them. The only negative thing I can say about them is that the rewards system is kind of difficult to figure out. Still, I definitely think it's worth a shot.
And don't forget, every time I add a new survey review, I also add it to the Paid Survey Directory (so it's always updated.)