Pretty much any time Alice kicks into high gear qualifies. Her fight against the Licker is just the beginning.
Everything involving Nemesis. From the excellent costume and make-up effects, to the mini-gun and rocket launcher gunfights, turning against Umbrella, and even sparing LJ because he was a civilian, Nemesis gets plenty of awesome moments throughout the film.
One moment near the movie climax shows how much of an Implacable Man he is. Alice impales his heart with a metal spike and drives him more onto it with more hits till she recognizes who he really is. Then when he is ordered to pick up his guns, he casually pulls himself off the spike and picks up his guns
Alice running down the side of a building. That stunt was done for real. Milla Jovovich's stunt double did the first half of the run 200 feet above the ground and Milla did the second half herself.
Near the end: "My name is Alice. And I remember everything."