- Tripoli Rocket Association - dedicated to high-powered rocketry
- Rick McKee's Arizona Rocket Consortium
- Superstition Spacemodeling Society (awesome project: Upscaled Estes Cherokee-D)
- Arizona High-Power Rocket Association (Tripoli) launches large Estes to M's monthly
- Experimental Rocket Association of Arizona (Serious shit)
- Rocket Motor Classification at Wikipedia
- FAQ on Amateur Rocketry at Rocketry.org
- Good introductory reference at Fly Rockets (includes legal issues, certification, where to buy)
- Winged Shadow Systems provides altimeters, airspeed, and other instrumentation designed primarily for R/C aircraft.
- Apogee Rockets carries the AltimeterOne and other cool stuff.
- Adept Rocketry sells instruments, including a $20 altimeter!