Including sources for weapons, tactics, training, organization, etc.
Jane's is a provider of "defense, geopolitical, transport and law enforcement information." A great source for a modern military game.
Industrial and Military 3D Computer Models
Web Sites for the:
United States Army Main Web Site, and Yahoo sites for "US Army"
United States Navy (Office of Naval Intelligence), and Yahoo sites of "US Navy"
United States Air Force and Yahoo sites for "US Air Force"
Civil Air Patrol (Southeast HQ)
United States Marines and Yahoo sites for "Marines"
United States Coast Guard
Soviet (Russian) Weapons and Arms Systems from the Moscow Institute of Physics and Technology