airline issued postcards
publisher postcards
safety cards
links to other aviation postcard sites:
Christian Gerbich's Airline Postcard Swap Page
Mike Charlton's Postcard Site
Aviation Postcards KT
Takashi Yamaguchi
Bill's Postcard Page
Helicopter Postcards Reference Page
Aerobernie
Odd
Robin
j.j. postcards
John Schmidt
airline colors
I also have lots of airline stickers that are available in exchange for postcards.