Gratis Network's sites are not scams. Here's how they work.
1. You sign up.
2. You're given a list of trial offers from various companies (eBay, AOL, and others... most are well-known). You must sign up for one of these offers. Once you've signed up, the company confirms this to Gratis. Gratis gets money for the referral; you get credit for completion. (Most offers are free trials, so once you're credited you can just cancel. Check the details before you sign up.)
3. Get a few friends to do the same thing. (Depending on the site, you need 3, 5, or 10 others to sign up with your referral code.)
The reason they don't need to scam you is because people think it's a scam anyway. Let's look at Csquared ("Cspace2" as he now chooses to be called

) for instance. He signed up and completed an offer from Blockbuster. Blockbuster paid Gratis for referring him. But now, Csquared needs to find 10 other people to sign up. He asked you guys. You seem to think it's a scam, so you won't sign up. Because he can't find anyone to sign up, he won't complete his required 10 referrals, and Gratis makes a profit because they didn't actually have to send him his iPod Photo.
So they make enough money off the people who
don't complete their referrals that they can afford to send the prizes to people who
do complete them. (Incidently, they actually lose money whenever they send out a prize.)
Head to
http://www.gratisnetwork.com/ to see all their sites.
Those who will remember, will speak fondly of the warm morning breeze.