Toluna is one of the highest rated survey companies.
They have the best rewards, and the highest access to surveys.
Some of the top rewards are:
Gap Gift Card
Gas Gift Card
Sephora Gift Card
$4500 Sweepstakes Drawing
As usual, signup is free, and you can see what surveys are available when you click on this link.
The signup is simple, its just on the homepage and takes 5 minutes or less.