Hardware:
  Marshall
  Line 6
  Groove Tubes
  Fender
  

Informational Web Sites:
  Digital Domain
  Harmony Central
  ProRec

Promotional Web Sites:
  cdbaby.com

Magazines:
  Electronic Musician
  EQ

Copyright information:
  US Copyright Office
  Kohn on Music Licensing

MIDI:
  MIDI Manufacturers Association

Buy stuff:
  Musician's Friend
  Cassette House
  zZounds.com