Wow! You can get a free $20 gift card from Plum District by referring four people and getting them to sign up. They do not need to make a purchase, just sign up!
*UPDATE: This offer had A LOT of problems, including bad links, slow emails and people not getting credit. In any case, it is now closed to new participants. If you already signed up you have until midnight 3/11/11 to get your referrals.