Carnegie Mellon Computer Music Group - Research in real-time control, acoustic signal processing, music synthesis, music understanding, and performance.
International Computer Music Association (ICMA) - Individuals and institutions involved in the technical, creative, and performance aspects of computer music. For composers, software and hardware developers, researchers, and musicians.
Kaon - Non-profit organization dealing with experimental, concrete, electronic and environmental music.
MIDI Manufacturers Association - Develops Musical Instrument Digital Interface standards. MIDI is a very commonly used format.
Music Cognition Group - Research in music cognition, music representation, and music technology. (Formerly known as Music Mind Machine)