These codes are still working! You can use them once per credit card.
DVDKROG (good at Kroger stores)
DVDATWAG ( good at Walgreens only)
found at Inside Redbox
Kroger also has codes that come out of the catalina machine (is that what it's called?). When we were camping in Moab last weekend (with 2 small kids---don't recommend it) we went to City Market. A kid in front of me didn't even check and left me with 2 free redbox codes. They printed from that sweet sweet machine. Maybe he did notice and wanted to be nice...lol...