Have you heard of PineCone Research? They are a company that sends out surveys via email to people who have signed up with them, asking their opinions on products along with questions about their shopping habits.
A few months ago, I signed up with them during one of their enrollment periods. They started sending me surveys soon after. Each time I complete a survey, they pay me $3. That's not much, but it helps. They pay me about 2-3 days afterward through PayPal. That means I can let the money sit in PayPal and use it the next time I buy something off eBay or from another merchant who uses PayPal, or I have the ability to transfer it into my checking account.
If you're interested, go here to sign up. The enrollment period is only open for a short time.