Gotta join in with everyone saying Inglourious Basterds.
I'm not sure whether opening here refers to just the first little bit, the first scene, the first act, I guess it can be anything. One I really like is the opening of Alien, literally just the intro with the title of the movie appearing bit by bit. Ridley Scott kinda ruined it by doing it again in other movies, but that first time was cool.
Also, I can't be here and not post this.
It's been a while since I last said it, but it's still very much the case that this is the best movie ever made.