Get a free DVD rental at your local Blockbuster Express! Simply use code: SSD19B (exp. 9/30). There's also a code GA19B4 (exp. 10/31) that's good for buy one get one free rentals, but they cannot be combined -- perfect for a movie night though!
These can be used once per debit/credit card, so you can rent more than one for free by using different cards.
(Thanks, Madame Deals!)