Right now you can use code F2AMA8TG3 to get a free one night rental.
The expiration of this code is 5/8/13 though sometimes they pull them sooner.
I have to run out the door so I can’t check but usually you can use these codes when you reserve online  as well!
Also I am seeing the code ZVX2JW2J for $.50 off but no mention of an expiration date!
Let me know if they work!