JSyn - modular synthesis API for Java.
JMSL - Java Music Specification Language
PortAudio - cross platform audio I/O API for 'C'

Downloadable Music

This site is for experimental, software based, computer music. There are hundreds of musicians that I like but I only link to computer music or very experimental music sites. So please don't ask me to link to sites containing rock, jazz, pop, synth-pop, dance, folk or other types of music.