Various museums across the US are participating in free admission on Saturday, 26 Sept 09. The link below takes you to a searchable site. The Florida Air Museum in Lakeland is one of the museums participating that my family will be visiting.
Other aviation museums I saw were:
Aerospace Museum of California
Atomic Testing Museum
CAF Airpower Museum
College Park Aviation Museum
San Diego Air & Space Museum
The Museum of Flight
The National World War II Museum
U.S. Space & Rocket Center
Enjoy free general admission for you and a guest to hundreds of museums and cultural venues nationwide on Saturday, September 26, 2009.