WWII in Color website has the Internet's largest collection of rare color photographs from World War II. This one above is a signed photo of the Flying Tigers in China.
Flying Tigers was a volunteer group of pilots and ground crew, recruited under a secret presidential order by Roosevelt to fight Japanese forces (under disguise that they're part of the Chinese Air Force) before Japan attacked Pearl Harbor.
Link - Thanks Algonkin!
See also the story about the Flying Tigers here: The Truth About Pearl Harbor.