There's a lot of sad Doom music, if you're into that. Some are pretty simple too, so you should be able to pick them up quick.
A little while ago tonight I was humming a tune I couldn't quite place, but I loaded a few of my favorite PWADs until I found it. It was Requiem MAP06 (Mines of Death). I played for a bit since it's been a while and I long forget most of the level. Got up to the red key and saved the game (I need to sleep, been a long day).