Was thinking of this while watching Twin Peaks:
David Lynch and Angelo Badalamenti
Ingmar Bergman and Sven Nyqist
Ming-liang Tsai and Kang-sheng Lee
Martin Scorsese and Thelma Schoonmaker
Akira Kurosawa and Toshiro Mifune
I also have to say Joel and Ethan Coen, who would probably appear on just about anyone's list.