I've included a couple of my own Commodore 64 tunes for you to play around with (and hopefully enjoy listening to). They are included in both original C64 executable format (*.C64) as well as in PSID (*.SID) format.
The files reside in SIDs\* and are:
The files are (C)opyright 1992 me, "Artificial Arts" and "LASER Inc."
Enjoy!