John Romero of long pretty pony hair fame (as well as some sort of role on Doom, I forget) has posted a blog update talking about rooting through the Doom development data and coming up with a whole bunch of unused Doom MIDIs created by Bobby Prince back in the day. Says he:
There's a reason these weren't released - they're not very good, at least not as great as the music we actually shipped with the game. Some of the songs are just repetitive riffs.
So yeah, go listen or something.