If you submit your details to this website you will receive a free dvd. I did this and it was received within a week. I suggest that you enter an email address that you don't mind having advertising sent to, although you can remove your details from their database after the dvd has been received.
Not the greatest selection of dvds but the 'Shawshank Redemption' is worthwhile on it's own and with that you also get 3 more films.
A big thanks to Rooban for this comment - Go through Topcashback or Quidco and you'll get some cash too! (Rep added)