I'm not really into comic books, but with that said:
Sin City (though ive never even seen an issue of the book)
Batman Begins
Spiderman 2 was superior to the first, but was still ruined by excessive man bewbs
V for Vendetta was good, but I don't understand why everyone was telling me its one of the best movies of all time.
A History of Violence (I credit Johnlindsey for informing me this was based on a graphic novel). I really liked this movie, though I feel the crime boss brother was miscast. He was a goofball.