If you happen to have a kiosk nearby, you can get aby using the code CKVPX9A7, which is valid through July 27. If you miss out on that, you can use code CKVPX9B7 between July 27 and August 10 for a “rent one DVD, get one free” deal.
Good luck finding a kiosk, though. From my quick glance, I think most of them are in Florida with a few in other large cities (San Jose, Houston, OKC, Dayton, etc). I'm just hope Blockbuster's foray into movie kiosks will get Redbox to bring back their weekly free DVD rental codes. This once-a-month deal just isn't cutting it for me!