I think the <b>Jarhead</b> trailer was amazing. If the theater really rocked the Kanye....you had to go see it.

Another vote for Dark City. The temp music was awesome, I was disapointed they didn't use it in the movie.

Others:
The Thing (Carpenter's; very creepy with the opening radio transmission)
THX 1138 (the re-release trailers)
Vanilla Sky (the Times Square teaser)
Star Wars: ROTS (the Vader/"Rise" teaser)