I do not condone paying for iPhone apps, but this one will make you money if you use it just once. Just once!
The $.99 Red Box FREE Rental Promo Codes app shares codes for free one-night movie rentals from Redbox, those DVD kiosks at chain grocers and drugstores. Each night is $1 so if you keep the DVD more than a day, you pay.
The app shares new codes twice a day and grades the validity of the codes with a green, yellow, or red light. You can also vote if each code worked for you.
iPhone app for free movie rentals