Redbox puts out a FREE CODE for their movies on the 1st Monday of each month. And if you use different debit/credit cards to purchase them, then you can use the code again for each card. But remember that it is only free the first night! This month's code is GN34D7Z.
UPDATE: I just read that this will be the last time they will be giving a generic code and that now you will have to sign up HERE to have them text you a unique one time use code.