"Monty Python and the Holy Grail", "Raiders of the Lost Ark", "The Lord of the Rings: The Fellowship of the Ring", and "Memento"... especially "Memento".

The Matrix, The way of the Gun http://www.youtube.com/watch?v=5xsaMcw69D8 (too funny) and THE DARK KNIGHT...A BITTERSWEET LIFE

I don't know if it's my all-time favorite, but the opening scene of "Duplicity" -- Paul Giamatti and Tom Wilkinson duking it out in slo-mo on the tarmac as their entourages watch - was pretty great.

Way of the Gun I think that Sara Silverman is one of the least funny comics, especially when held up against her hype. However, she delivers some of the most grotesquely funny insults in the first five minutes of an otherwise totally forgettable movie. When I heard it the first time I was agape and unable to laugh. My second time through I had to pause it multiple times to get over bouts of silent hysterical laughing.

The Wedding at the Godfather. Luca Brasi rehearsing what he is going to say to Don Corleone, the great music, Sonny sneaking off with the bridesmaid, Don Corleone dancing with his daughter. The opening was as good as a movie climax scene. Honorable mention to most of the James Bond films.

The opening to Fargo where Jerry goes to talk to Carl and Gerer in the bar. It sets up the story and drew me in, in such a way that I was fixed on the movie from that point on, and all from a movie I didn't expect to like.