I include comedies because IMHO it is just as tough to make a great comedy as a great drama.
1) Shawshank
2) Bowfinger (Steve Martin's best movie since the early 1980s)
3) Fight Club
4) The Waterboy (we need some Adam Sandler up here, but we could easily have Billy Madison).
5) Run Ronnie Run (this was done by the Mr. Show people and wasn't even released in theaters, but is still one of the funniest movies that I have ever seen)
Honorable mention to Ace Ventura (the first one), Liar Liar, Me Myself and Irene, Oh Brother Where art thou?, Tommy Boy and Thank You for Not Smoking, Silence of the Lambs, The Truman Show, Fifth Element and Total Recall