Rydia.net-The nice people who let me host my website
American Composers Forum-Great resource for composer-related opportunities. Based in Minnesota
ASCAP-It's either this of BMI. If you're a composer you should be a member of one of the two.
Band Resource-Brand new website for all things related to wind-band music.  Expect it to get bigger in the upcoming months
Game Audio Network Guild- For those interested in the audio side of video games.
International Alliance of Women in Music- If you're a woman...
International Clarinetist Association
International Game Developers Association
Kappa Kappa Psi- Coed service fraternity for college band members
University of New Hampshire Department of Music- my undergraduate alma mater
University of Minnesota School of Music- my graduate alma mater

Yuval Ron- Composer
Judith Zaimont, Composer
Doug Geers, Composer
Mike Annicchiarico, Composer
Andrew Boysen Jr, Conductor/Composer

Jennifer Quick, Freelance Artist
Craig Levesque, Composer/Theorist
Jocelyn Hagen, Composer
Andrea Veal, Soprano
Others whose links may be broken...