Quite a few of us grok mup, which is a fairly legible textual format. Unfortunately, the software that converts it into postscript or MIDI, while being available as source code, isn't free of charge.

Personaly I have an even more serious soft spot for the music notation used by AMPLE, which isn't designed to be converted nicely into staff notation but is much easier on the (well, my) eye in textual form. But the software died with the BBC Micro platform; I keep feeling I should resurrect it.