On line shopping:
Ace Hobbies
Balsa USA (Kits & wood)
Batteries America
Bocca Bearing
Cyberheli Hobby Shop
Global Hobby Distributors
Heli Proz
Helicopter World (Century)
Hobbies & Helis International
Hobby Lobby
Hobby Shack  (Now Hobby People)
Horizon Hobby (JR Importer)
Just Canopies (Heli canopy painting)
McMaster-Carr (Hardware)
Micro Fastener (Bolts & stuff)
Mr Carbon 
MTA Hobbies
Radical RC (Batteries & more)
RC Power Supply
Ricks R/C Heli
Sheldon Hobbies
Tower Hobbies
Zooms Helis

Forums:
Ezone (Electric Flight)
Helifreak
RC Universe
Rotary Modeler
RunRyder
RCHelispot

Simulators:
FMS Flight Simulator
Pre Flight Simulator
Real Flight Simulator

Manufactures:
Airtronics Radio
Astro Flight
Bergen Helicopters
CSM Simulator and Gyro's
DuBro Products
Futaba
Heli-Max
Hitec radios
JR Radio (Japan)
Kyosho
LMH (Light machine helicopters)
Macs Products (Exhaust systems)
Magnum Fuel
OS Engines
Performance Specialties
Ritchs Brew (Fuel)
SIG Manufacturing
Super Tiger Engines
Thunder Tiger Engines
Top Flight
X-Cell Helicopters

Other:
AMA--Academy of model aeronautics
Battery clinic (Good battery information)
Curtis Youngblood homepage
Electronics Projects for R/C
Electric R/CHelicopters (Links & info)
FAI F3C Competition
FCC cfr-95 ruling
John Vugts (Nederland - General information)
Micro heli eBook (Contents unknown)
Model Airplane News
RC Modeler magazine
R/C Circuits (Joystick interfaces)
Scale RC Helis
Sirius Electronics (Diode jumpering)
W3MH (World Wide Web Model Helicopter)