I try to post these as I come across them!
New code is 9HB6MP22. This code is good for one FREE rental at any Redbox Movie Kiosk. To use the code, select "rent with a code". Each code can be used once per credit/debit card. The $1 rental fee is credited back to your account when you return the movie.
Some old codes that are still working:
These are supposed to only be for Walgreens stores, but have been reported to work at Walmart also.
Enjoy your FREE movies!