Without giving away too much, market research studies are crazy low hanging fruit...

Within the last 3 weeks, I've signed up and participated in 5 market research studies, totalling about $660. I have another 4 studies scheduled to add about $450.

In terms of time and money gained, these are absolute gold.

Highly recommend looking at both local and national research companies to maximize your chances of being picked. Sign up for all of them and check their facebook/sites daily for updates.