http://forums.dansdeals.com/index.php?topic=3802.0
the short version: (in case you don't want REALLY NUMB LEGS!)
call the number on the back of your card, enroll in an airline. you will now get reimbursed for up to $200 of expenses (non-ticket) paid to that airline(only the one you enrolled in)for each
calender year. Examples would be baggage charges or upgraded seat charges. through a glitch in the system Amex, Gift cards in smaller denominations also get reimbursed. the preferred methods of using these credits are to buy 2*$100 AA gift cards (as AA allows you to stack up to 8 gc's towards a flight) in
TWO SEPERATE TRANSACTIONS(so that it comes up as two seperate $100 dollar charge and not one $200 charge which wouldn't get reimbursed).
The other good option is"the PlatinumGuy's Grand Mehalach", this is to buy flights on delta, pay more than $200 towards EC seating (prefferred seating, use several legs if necessary). Cancel the flights within 24 hours, since it takes awhile for delta to actually reverse charges, there is ample time to get reimbursed from Amex before the charge dissapears. this affectively leaves you with a $200 statement credit. Good Luck