Office Space - The Michael Bolton rapping in traffic scene

Fight Club - The CGI through the brain thing is kinda neat.

Mean Streets - It's no secret that Scorsese loves his city and Phil Spector songs. Gotta love the authenticity and rawness of this home video styled intro.

American Splendor - Could just be the comic head in me, but I think this was an innovative idea and a brilliant execution. I imagine it was a bit of a no-brainer to say "let's make the opening credits look like a comic book", but the way they pulled it off was well thought out and it looked awesome.