There are sooo many to come to mind, I'll just list the ones I recently purchased + some:
John Komeda's "Rosemary's Baby"
Michel Legrand's "The Thomas Crown Affair"

+ gotta mention"
"Car Wash" one of the ultimate fun soundtracks

+ lil bit more obscure:
"A Hero's Not A Sandwhich," funky 70's soundtrack which prominently featured Hubert Laws

John Dankworth—Modesty Blaise, The Servant, Return from the Ashes
Lalo Schifrin—The Liquidator, Once a Thief, Joy House, Bullitt
John Lewis/MJQ—Odds Against Tomorrow
Michel Legrand—Umbrellas of Cherbourg, Young Girls of Rochefort, Thomas Crown Affair
Quincy—Walk Don't Run, In Cold Blood, For Love of Ivy
and of course Duke Ellington—Anatomy of a Murder

Fight Club
Virgin Suicides
Waking Life
Reqiuem for a dream
Punch Drunk love
Eternal Sunshine..Basically anything Jon Brion works on

and both kill bills

triplets of belleville
one hour photo
star wars (episodes 4-6)
2001: a space odyssey

American Pimp

Forgot a couple more

"Alfie"(the original one with Michael Caine)- Sonny Rollins
"Blow Up" - Herbie Hancock

"Midnight Cowboy" Soundtrack - John Barry
"Falcon & The Snowman" - Pat Metheny Group
"Short Eyes"-Curtis Mayfield
"Black Ceasar" - James Brown

Superfly - Curtis Mayfield
Just for "Give Me Your Love" alone. This soundtrack embodied an era. Pimp glam exists today because of this movie! And this soundtrack was it's theme!!

if any of you are into funk, i'd suggest the baadasssss!!! soundtrack... great album, classic material.

i am sam ost is great, too. beatles remakes? can't beat 'em.

oh, and garden state ost. zero 7's one of my fav's, and the rest of the songs are great, too... one of those 'listen to it from front to back' albums

"Jackie Brown" OST
"Carlito's Way" OST
"Shaft" OST