Here's a site I'd seen some time ago, but lost the address to:
Dark Side of Phobos. It's a (free downloadable) album of remakes of the music from the original Doom game. Novelty aside, it's all pretty decent (if a bit 1990s-industrial-techno feeling).
That's it. I need to learn to play the (electric) guitar, if only so I can make the kickass rendition of the M.U.L.E. theme I've been dreaming of.