I think there are two categories, musical and non-musical movie soundtracks.
Non-Musical:
The Virgin Suicides
The Royal Tenenbaums
The Life Aquatic with Steve Zissou
Kill Bill: Vol. 1
Eternal Sunshine of the Spotless Mind
Vanilla Sky
O Brother, Where Art Thou?
The Graduate
Good Will Hunting
Magnolia
Pulp Fiction
Musical:
The Sound of Music
Meet Me in St. Louis
Hello, Dolly!
The Music Man
Mary Poppins