The home page for NAfME, the National Association for Music Education (formerly known as MENC, Music Educators National Conference)
An extensive list of resources related to teaching music
K-12 Resources for Music Educators
As the name states, this site contains an amazing number of links for band, choir, orchestra, compositions, lesson plans, instruments, workshops, etc.
Chad Criswell's blog--a good resource for all music educators
Educational Cyberplayground Music Channel
A site with off-beat information about music education
Research Perspectives in Music Education (RPME)
You can submit or read papers relating to music education at this site for RPME, the official refereed research journal of the Florida Music Educator's Association.