Some of mine, in no particular order:

The train scene in Spider-Man 2.
Azula's nervous breakdown and her and Zuko's duel in the series finale of Avatar: The Last Airbender.
Luke and Vader in The Empire Strikes Back.
The "define dancing" scene in Wall-E.
The Beast's transformation in Beauty and the Beast, and also the Prologue of that movie.
That moment in The Prestige where you figure out Alfred's secret.
In the most recent Pride and Prejudice movie, the scene where Elizabeth meets Georgiana and Mr. Darcy smiles for the first time in the whole damn movie. It's a thing of beauty.

This is a good thread! I can't wait to hear what other people say.