Anything by Martin Galway on C64 OWNS!!, game soundtracks like Wizball, Parallax, Green Beret, Ocean Loaders, Arkanoid, Combat School etc.
Also anything Tim Follin done on the C64 was awesome to, like Ghouls+Ghousts, Bionic Commando..
Rub Hubbard did a lot of great C64 soundtracks as well, to...