In addition to the National Museum of the United States Air Force, located at Wright-Patterson Air Force Base, Ohio, the USAF operates several field museums and heritage centers. Please call ahead as some may not be open to the public. They are:

Air Force Armament Museum - Eglin AFB, Fla.
Air Force Flight Test Center Museum - Edwards AFB, Calif.
Air Force Space and Missile Museum - Cape Canaveral AFS, Fla.
Air Mobility Command Museum - Dover AFB, Del.
Barksdale Global Power Museum - Barksdale AFB, La.
Enlisted Heritage Research Institute - Maxwell AFB, Ala.
Hill Aerospace Museum - Hill AFB, Utah
Malmstrom AFB Museum - Malmstrom AFB, Mont.
McChord Heritage Center - McChord AFB, Wash.
Museum of Aviation - Robins AFB, Ga.
Peterson Air and Space Museum - Peterson AFB, Colo.
Sheppard AFB Heritage Center - Shepperd AFB, Texas
South Dakota Air and Space Museum - Ellsworth AFB, S.D.
Travis AFB Heritage Center - Travis AFB, Calif.
USAF Airman Heritage Museum - Lackland AFB, Texas
Warren ICBM and Heritage Museum - F.E. Warren AFB, Wyo.

There are numerous military and civilian aviation museums in the United States and abroad. Here are links to a few museums:

390th Memorial Museum - Tucson, Ariz.
Aerospace Museum of California - McClellan, Calif.
American Airpower Heritage Museum - Midland, Texas
American Airpower Museum - Farmingdale, N.Y.
Canada Aviation Museum - Ottawa, Ontario, Canda
Canadian Warplane Heritage Museum - Mount Hope, Ontario, Canada
Castle Air Museum - Atwater, Calif.
Cradle of Aviation Museum - Garden City, N.Y.
De Havilland Aircraft Heritage Centre - Hertfordshire, United Kingdom
Evergreen Aviation and Space Museum - McMinnville, Ore.
Flying Leathernecks Aviation Museum - San Diego, Calif.
Flying Tiger Historical Organization - Guilin, China
French Aviation and Space Museum - Le Bourget, France
Glenn H. Curtiss Museum - Hammondsport, N.Y.
Grissom Air Museum - Peru, Ind.
Hickory Aviation Museum - Hickory, N.C.
Historic Aviation Memorial Museum - Tyler, Texas
Imperial War Museums - United Kingdom 
Intrepid Sea, Air & Space Museum - New York, N.Y.
Kansas Aviation Museum - Wichita, Kan.
Kansas Cosmosphere & Space Center - Hutchinson, Kan.
Lone Star Flight Museum - Galveston, Texas
Louisville Naval Museum - Louisville, Ky.
MAPS Air Museum - North Canton, Ohio
March Field Air Museum - Riverside, Calif.
Motts Military Museum - Groveport, Ohio
Museum of Flight - Seattle, Wash.
National Aeronautics & Space Administration (NASA) (photo collection) 
National Aviation Hall of Fame (located in the National Museum of the U.S. Air Force)
National Museum of the Marine Corps - Triangle, Va.
National Museum of the Mighty Eighth Air Force - Pooler, Ga.
National Naval Aviation Museum - NAS Pensacola, Fla.
National WASP World War II Museum - Sweetwater, Texas
Octave Chanute Aerospace Museum - Rantoul, Ill.
Pacific Aviation Museum - Ford Island, Hawaii
Pima Air & Space Museum - Tucson, Ariz.
Royal Air Force Museum - London and Cosford, United Kingdom
Royal Australian Air Force Museum - RAAF Williams Point Cook, Victoria, Australia
Royal New Zealand Air Force Museum - Christchurch, New Zealand
San Diego Air & Space Museum - San Diego, Calif.
Silent Wings Museum - Lubbock, Texas
Smithsonian, National Air & Space Museum - Washington, D.C. and Chantilly, Va.
Strategic Air Command & Aerospace Museum - Ashland, Neb.
Titan Missile Museum - Sahuarita, Ariz.
U.S. Army Aviation Museum - Fort Rucker, Ala.
WACO Air Museum - Troy, Ohio
Wings of Eagles Discovery Center - Horseheads, N.Y.
Wings Over the Rockies Air & Space Museum - Denver, Colo.
Yankee Air Museum - Belleville, Mich.