Get $20 for signing up for American Express' Paypal-like service called Serve

(expires January 5)

American Express has a Paypal-like service called Serve that lets you send money by e-mail.  Until January 5th, you get a $10 bonus in your account for signing up.  Then, after you sign up, you can play a simple trivia gave to get another $10 deposited in your account (after a business day or so).  You can also fund your account with a credit card without fees (for now), up to $250 to pick up some token miles or cash back.  You can also refer your friends to get $5 for each referral.  You'll need to enter some identifying details like the last 4 of your social security number.