I really enjoy good trailers, here are some of my favorites (some of these movies aren't for younger viewers):

Rosemary's Baby - is a really creepy trailer that tells you almost nothing about the film, but it gives you a great idea of the films mood.

Dr Stranglove: Or How I Learned to stop Worrying and Love the Bomb - I love the editing and plunky music on this.

Amores Perros - Love the music and rapid editing. (took me a while to find this version of the trailer that wasn't on Netflix)

The Shinning - one shot, no actors and gives nothing away.

Europa - This is how an announcer on a trailer should sound

Time Bandits - "Men made up to look like monsters, monsters made up to look like men!"

Post your favorites, if the trailer contain spoilers please warn people, and please give links, sometimes there is more then one trailer.