The following links are to University Studies. Some pay, some are for contests, but ALL the studies are pretty fun.
I have personally won a few $50 gift cards from these sites.
NOTE: If you do sign up, you must check the site to view new studies because most do not send email alerts.
Stanford Behavior Lab
Stanford Psych
Princeton
Center for Decision Research at the University of Chicago
UCLA
Yale
Kellogg School of Management
