This list started as a top 10, but I could not force myself to stop there. Certain directors are particularly good at pulling soundtracks together. I could easily expand my list by just further considering David Lynch and Stanley Kubrick films.
My top 12 (in no particular order):
- Joe Strummer: The Future is Unwritten (Elvis's "Crawfish"; Strummer's "Johnny Appleseed"; etc., etc.)
- Dead Man Walking (sonic quality is excellent)
- The Apostle (another sonic gem)
- Juno (Sonic Youth; Kimya Dawson; The Kinks; etc.)
- Trainspotting (Iggy Pop; Lou Reed; New Order; etc.
- Twin Peaks (as stated above, Lynch has a number of outstanding soundtracks, especially those featuring Angelo Badalamenti)
- O Brother Where Art Thou? (great sonic quality and some cool spirituals)
- Thin Red Line (spooky)
- Pat Garrett & Billy the Kid (one of my favorite Bob Dylan albums)
- Into the Wild (Eddie Vedder is one of my favorite vocalist)
- Mad Men Christmas (the TV show has numerous great songs peppered throughout the seasons)
- Where the Wild Things Are (Karen O's cover of "Worried Shoes" by Daniel Johnston is incredible and a stark contrast to his version)