All of Wes Anderson's movies have great soundtracks: Rushmore finishes on 'Ohh La La' by The Faces; The Royal Tenenbaums features The Clash, Ramones, The Velvet Underground AND Bob Dylan; while The Life Aquatic manages to mix Bowie covers sang in Portuguese and 'Search And Destroy' by The Stooges. That's class.
Tarantino also mixes a nice line in soundtracks, as do the Coen brothers. Oh, and special mention should go to Ghost Dog: Way Of The Samurai - the whole soundtrack is put together by RZA. It's dope, yo, ese, homie, bro, etc.
I've always been a fan of disney soundtracks.
My all time favorite is High School Musical. I really think its the awesomest soundtrack ever. It's all i listen to now.
My second fav CD from Disney is Hercules.
I do have other soundtracks but they are not very "adultish". IM 14 and Im stuck in the 5-10's
Some others I'll mention:
Requiem for a Dream (already mentioned it earlier in the thread, but might as well say it again, great music).
Oldboy
Cannibal Holocaust (say what you want about the movie, the music is amazing).
A Very Long Engagement.
Brokeback Mountain
The Shining
Platoon/Elephant Man (Both share the same main song, and said song is incredibly effective in both films)
Shawshank Redemption.
Crash (Great ambient music, really fits the atmosphere).
Sin City
Sweet Hereafter
All Tarantino films.
Palindromes
American Beauty
Amelie
Collateral
Forrest Gump
One Flew Over the Cuckoo's Nest (Again, great ambient music, fits beautifully with the film)
Paths of Glory (More or less for the song the woman sings at the end, it's quite legendary).
South Park: Bigger Longer Uncut
Team America
Braveheart.
The Good The Bad And The Ugly is classic.
Ry Cooder's Soundtrack for Paris,Texas I like.
Phillip Glass' compisition for Koyaanisqatsi
and
Thomas Newman's score for Fried Green Tomatoes
I also like his score for The Shawshank Redemption which was mentioned in the previous post. In fact, Backfire made quite a few good picks.
in terms of original scores
and i terms of songs not written directly for movies
from "this is England"
YouTube video
the open scene from "mean streets" with Jumpin' Jack flash by the stones