V for Vendetta, Prince of Persia, Batman Begins, The Dark Knight, Spiderman 2, Xmen, and some others as well.
Those are only movies that I think are good and where I know some of the reference material. V for Vendetta and Prince of Persia stray from that material (although Prince of Persia more so), and I think its great when you can have two different interpretations of the material that can live side by side. The Prince of Persia movie wasn't all that related to the game, but still used the material to create a good movie. Oh, and Spiderman 2 is the only good Spiderman live action movie so far.
There are other movies as well of course, I love Watchmen, but I have no experience with the background material, so I won't comment on it.