I think it would be neat if Stefan would add support of .mod music.
I don't know that much about the formatting and things, but I do know that .mod, .s3m, .xm, and .it are better than midi. Plus, with mod formats, you can do internal looping of songs and effectively, have 3 songs in 1 file all useing the same samples.
http://www.modplug.com <--go there to get ModPlug Player which is specifically designed to play module music formats.
I have a few mods on my ftp that do what I explained earlier, as far as internal looping and so forth. However, .it and .xm formats are closer to midi but like .mod and .s3m, you can still define your own instrument samples...but you can do extra stuff to the samples in the tracker for .it and .xm
It would be great to have an npc command to jump to different positions in a mod so that if you are in one room, the music is a certain loop then when you go to a new room, the position is jumped to a new loop.
Mods do get big, however, depending upon the number of samples and the quality of the samples used. Probably the largest mod I have is roughly 900k in size, but that is about it.
Btw, ModPlug central also has ModPlug Tracker which is used to track (make) mod, s3m, it, and xm formats.
Nothing wrong with midis, but sometimes, they just plain suck
Oh, and here are links to a few of my mods:
http://home.earthlink.net/~skittles00/CV_MAGIC.MOD
http://home.earthlink.net/~skittles00/frcremix.it
http://home.earthlink.net/~skittles00/CANYOUFL.S3M
http://home.earthlink.net/~skittles00/mcintyre.xm
one more thing, with these formats, you can also add voice effects that are better than the simple oohs and ahhs that midis have

even actual lyrics.
Winamp is okay, but sucks at playing mods, so use modplug player
