The new Keira Knightley movie, Atonement, is slated to open in limited release in the US on December 7th. Glam Girl Maria wrote asking where she can get a dress similar to the one Keira wears in the film. The figure-hugging 1930s dress in the movie was designed by the film's costumer, Jacqueline Durran.
For a close match, which you can customize, your best bet is to make one from Vogue Pattern V7365:
If making one is not an option, you can get a similar, if not exact, 1930s feel in a lovely green dress by David Meister: