Shadow of the Beast - Amiga
The Last Ninja - C64
Monty on the Run - C64
Harlequin - Amiga
I agree with Bigpops, its quite unusual to find games now days that have a unique soundtrack created solely for that game. To often now game soundtracks are just a collection of in favour artists. It seems to be the RPG genre that holds onto the games soundtrack, mainly with orchestral scores. Which reminds me, all the Bioware RPGs had great scores.
In the past you could pretty much guess whether a piece of music was from a C64 or an Amiga game etc (same could be said for early consoles), they had a certain distinct sound and certain limitations had to be worked around to get something good from them and some of the stuff created despite those limitations was purely brilliant and unique. The sound of a console or home computer was a much a part of it as the graphics etc in the past, it was unique to that particular machine. That cant be said anymore, new consoles dont sound different to each other which isnt really a suprise when music is streamed from CD or file rather than created by hardware onboard.