Sorry for the double post...
Scooby, I'm sorry, but most of the nose arts that I found were in B&W or too small to be scanned. I've scanned only a few decent nose arts (WARNING! May be 56k unfriendly!):
An Italian nose art of WWII, seen on the Russian front

A RAF inisgnia

An Italian WWII insignia usually applied on torpedo bombers

Another Italian WWII torpedo bomber insignia

English nose art applied on a Spitfire

German nose art applied on a Bf-109

Insignia of a Washington ANG squadron

Nose art on a B-17 used in Italy

Nose art on a P-38 used in Italy

Nose art applied on James Doolittle's B-25 for the Tokyo Raid

If you want also some Italian Air Force logos, just tell me.
EDIT: Whew! I thought the images were much smaller!

Well, I'm sorry...