It is an interesting trend in the airline industry. Coupons.
The economy is in the dumps and the airlines are fighting for your money. To try and get your money, they have decided to jump in to the coupon/coupon code game. This is an interesting shift as airlines typically don't play this game.
It appears that the only way to receive the coupon codes is by signing up for individual airlines email alerts. That's not too much to ask if it saves you a fair amount of money. You also have to book on the specific airlines website. (Although, that is what I prefer versus booking via a discount site.)
Here is an example from Air France. The coupon code is MARCH442 and will save you $75. You must use the code to purchase a ticket by February 17.