Australasian Computer Music Association
Forum for new compositions, information sharing, and research about music technology and computer music.
http://www.acma.asn.au/

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.
http://www.computermusic.org/

Interactive Audio Special Interest Group
For developers of audio software, hardware, and content, to freely exchange ideas.
http://www.iasig.org/

MIDI Manufacturers Association
Develops Musical Instrument Digital Interface standards. MIDI is a very commonly used format.
http://www.midi.org

Columbia University Computer Music Center
Classes, events, facilities, projects, software, news.
http://music.columbia.edu/cmc

Music Cognition Group
Research in music cognition, music representation, and music technology. (Formerly known as Music Mind Machine)
http://www.hum.uva.nl/mmm

Electroacoustic
Collection of sites offering informatics, composition, and articles using music technology.
http://acusmatica.7host.com/electro/electro.htm

University of Plymouth Computer Music Research
Research programs focus on Evolution, Interaction, Synthesis and Cognition.
http://cmr.soc.plymouth.ac.uk/

New Interfaces for Musical Expression
Community page for the annual international NIME conference.
http://hct.ece.ubc.ca/nime/

SectionZ Electronic Music Community
Portal offering music searches by title, artist, genre, and mood. Forums, news, staff picks.
http://www.sectionz.com

Carnegie Mellon Computer Music Group
Research in real-time control, acoustic signal processing, music synthesis, music understanding, and performance.
http://www.cs.cmu.edu/~music/