Here's the scene from
O Brother, Where Art Thou? where they pick up Tommy Johnson from the famed crossroads:
http://www.youtube.com/watch?v=fgcWfVvT_UM
Great movie with great music, if you haven't seen it.
Ulysses Everett McGill: What'd the devil give you for your soul, Tommy?
Tommy Johnson: Well, he taught me to play this here guitar real good.
Delmar O'Donnell: Oh son, for that you sold your everlasting soul?
Tommy Johnson: Well, I wasn't usin' it.