In no particular order:
The Blues Brothers
Clue
The Princess Bride
King Kong (1933)
Night of the Living Dead (1968)
The Godfather 1 and 2
Stand By Me
A Christmas Carol (1951 and Disney's)
Jurassic Park
Alien and Aliens
Outside of the obvious, The Godfather 1 and 2 (3 was meh) and Goodfellas I really like The Departed, Once Upon A Time In America and Gomorrah.
Gomorrah is dark, gritty and eerily real feeling. There is also a TV show on Sundance I am anxiously waiting for Season 3 to come back. A little warning for those that don't like them, it does have subtitles.