Some good soundtracks I have bought not mentioned yet, I have dozens.

Holes
Camelot (Broadway Play)
Bagdad Cafe
Jesus Christ Superstar
Natural Born Killers
Lost in Translation
Sliver
Twin Peaks (TV Show)

I know it's not a movie, and I havent gotten around to buying the soundtrack just yet, but I've been very, VERY tempted to buy the soundtrack to Halo 2

Lost Highway
Private Parts (Howard Stern)
Natural Born Killers

magnolia
saturday night fever
grease
garden state
teenage mutant ninja turtles... go ninja go ninja go.

Beetlejuice
Pi
High Fidelity
Nightmare Before Christmas
Spy Game
13 Going on 30
Shrek
Run Lola Run
Donnie Darko
Matchstick Men
...

Really, the list goes on. I'm a media whore... a good 5% of my income goes into music and movies; if I can mix the two, I can't pass it up.

Lived to regret:
Flashdance
Goldeneye
Phantom of the Opera (saw it live when I was like 15)


Good buys:
All Star Wars soundtracks (about 14 or 15 total, I think)
LOTR 1,2,3
Gladiator
StarGate
Kill Bill 1,2
Catch Me if You Can
Minority Report
Jurasic Park
Empire Sun (yeah, I love John Williams)
Escaflowne

From Dusk Till Dawn

I don't know if this was mentioned but I bought 2 CD's from the movie.....

"Wedding Singer".

I love the music in that movie.

Just picked up Garden State - wonderful...

Some past classics:
Pretty in Pink
Repo Man
Blade Runner
A Boy Named Charlie Brown

I own:
All 3 Lord of the Rings
Amelie
Swingers
Sweet and Lowdown
O Brother, Where art Thou
Kill Bill vol. 1 and 2
Garden State
Daredevil(got it as a gift)
Bend it Like Beckham
Pulp Fiction

I'll admit it, The Lion King.

After seeing Kill Bill I wanted to go find the soundtrack RIGHT THEN, unfortunately it was 2am and nothing was open. (Thank god for mp3's!)

Highlander movie (the first one) soundtrack by Queen

Pulp Fiction
Young Guns II - IT WAS A LONG TIME AGO!
Oceans 11

All three Lord of the Rings
Pirates of the Carribean
Top Gun
Love Actually
Lost in Translation
Amelie

Garden State (awesome music!)
Bend it like Beckham
Pirates of the Carribean
Harry Potter 2 (whoo John Williams!)
Love Actually
Ever After (one song in particular I love on this soundtrack :D)
Footloose (I need a hero! lol. :P)
Tarzan (yah Phil Collins!)

The only 2 I can think of are De-Lovely and Clockwork Orange. I also have Forest Gump and Dazed And Confused, but they are not really soundtracks.