I signed up with MyPoints about three years ago, and have been clicking on their e-mails ever since.  For just about every e-mail they send you, when you click on the link contained within, it sends you to the website of whatever is being advertised in the e-mail, and your MyPoints account increases by 5 points.

Since most of the rewards are only available for thousands of points, it can take forever to accrue enough points, but once you do, the reward system is fast and easy to navigate, and you get your reward fairly quickly.

I'd recommend this program if you don't mind getting lots of e-mails...