Tim at Pop Crunch has a list of what he considers to be the best time travel stories ever. I think that he succumbs to the temptation of emphasizing archaic and high literature, but it's worth a browse.
As I've mentioned before, my favorite time travel story is The Man Who Folded Himself by David Gerrold.
What's your favorite (print or film) time travel story?
Link via Neatorama