I am going to throw out some original sound-tracks:
The Dark Knight: Zimmer & Newton Howard are on top form, and they really nail the disturbing yet tragic feel of the Joker in their 'themes' for him. There is one piano section in 'Why So Serious?' that is pretty much the tragedy of the Joker's origin story from 'The Killing Joke' in musical form. Amazing. The main 'Batman/Hero' theme is fucking rad, too.
Sunshine: I like soundtracks that can be listened back to on their own and manage to evoke the majority of the movie in images. A sign of a good and effective score. John Murphy deffinately manages that here. And of course 'On the Surface of the Sun' has become so famous, and rgiht fully so. So uplifting, yet eerily scary.
Requiem for a Dream: Clint Mansell works wonders for this movie. The soundtrack is probably the best thing about that movie aside from Ellen Burstyn's incredible performance. The main 'Requiem' theme, accompanying the ending of the movie is so stark, it simply cannot be 'unseen/heard'.
Star Wars: Need I say anymore? Episode V's is my personal favourite, but I love the entire series' scores. Too many notable moments to point out. *nerd-gasms*
On a side note, I saw Star Wars in Concert earlier this year. Very, very cool.