While this might look like a scam (like the many scams you've received in the past), this one looks like it's actually authentic. freeiPods.com is giving away free gifts ranging from gift certificates of $250.00 to a full 20GB iPod (or an iPod mini). I, myself, have signed up to get a free 2-week membership with BlockBusters DVD Rental (like NetFlix).
The only requirements is that you'll need to sign up for one and complete one of the many offers. My advice is to sign up for a BlockBuster account and then cancel just before the 2 week-trial period ends and they start billing you. This will still count towards your credit of completing their freeipods.com's offer.