Zachariah + Dewey Martin
Various Artists, Zachariah OST (Probe 1971)
Cool soundtrack featuring the James Gang, Country Joe & the Fish, Elvin Jones and some great scene-setting music by Jimmie Haskell. Haven't seen the movie, but not only did it star Don Johnson and a bunch of the musicians, but the clips available on Youtube make it look like a post-hippie Western version of Cop Rock.
The James Gang - "Laguna Salada"
The James Gang - "Country Fever"
Jimmie Haskell - "Camino"
Jimmie Haskell - "Matthew"
Soundtrack to this 1970 biker flick featured an ex-Buffalo Springfield member and his new band rockin out in a Leon Russell / Chilliwack "Seventeenth Summer" style. Loving this sound right now (and if we're talking 2008 might as well tack Quiet Village's "Gold Rush" onto the end of the acid cowboy roll call).
Dewey Martin and Medicine Ball - "Indian Child"