Besides all the Pay-to-Surf programs on the Internet, there are quite a few Paid-to-Click Programs. Some of these programs offer money and some offer points which can be redeemed for gift certificates. They make their money from advertisers, just like the Pay-to-Surf programs.
At MileSource, you can earn points for visiting sites, shopping, signing up for trials, & of course referring friends. The points aren't worth a set amount - it depends on your patience. You can get a $25 gift certificate for 3,500 points, $50 for 5,500, $100 for 9,000, or $150 for 12,000. If you exercise patience you are rewarded. The ClickFix area (points for visiting sites) lets you visit about 21 sites a day for 1 or 2 points each. You also get a percentage of the points earned by your referrals through 4 levels. They start you out with 1500 points for signing up and filling out a survey. Milesource gives Award Miles, which are good for free airline tickets, gift certificates, vacation packages, and merchandise.