Goodfellas: Michael Imperioli's performance in the scene where he actually stands up to Pesci. It's just a perfectly observed little bit of character acting.
The Age of Innocence: "He guessed himself to have been, for months, the center of countless silently observing eyes and patiently listening ears. He understood that, somehow, the separation between himself and the partner of his guilt had been achieved. And he knew that now the whole tribe had rallied around his wife. He was the prisoner in the center of an armed camp."
The Aviator: Alec Baldwin's quiet "Fuck". And the way the famous "blueprints" scene shifts from comedy to horror through sheer repetition.
The Departed: Mark Wahlberg's face in the final scene.
Shutter Island-Ben Kinglsey's creepy-ass delivery of "Baby, why you all wet?"
Hugo-Sacha Baron Cohen's anguished expression after his leg squeaks when he tries to approach Emily Mortimer.