Interesting to see a nice new collection of the DOS versions.
And of course there's the original Amiga versions on the Lemmings File Archive.
And the Sega Master System version can be found on SMS Power Music Archive.
And the Sega Mega Drive version can be found on Project 2612.
And the Windows versions can be found on VGMusic, erroneously listed under NES.
And the PSP versions of the past-tunes are coming as I record them from my PSP Brite... Links soon. :-)