I always liked the opening of "apocalypse now": The jungle, all quite and green, and then the helicopters, and suddenly all fire, while "The end" sounds.

"the apartment" is funny. You look the building, all people working, while hearing a lot of mathematical data about the company; and then you see jack lemmon working alone, stops saying things about the company, and tells you his personal problem, why he is there instead of home.

And "Muerte de un ciclista" (Juan Antonio Bardem, 1955), just amazing.

Besides, I like the opening with gandalf in "LOTR: The fellowship of the ring", the dialogue (specially the one about the tips) in "reservoir dogs", when Max von Sydow meets death in "the seventh seal" and the Korova pub in "a clockwork orange".