Here's another good one with camo and markings from almost every nation and specifics for many planes. The "US Interior colors" section also has exterior colors listed in many places and color reference photos. US is towards the bottom.
http://ipmsstockholm.org/helpdesk.asp#camouflage_markings
The basic progression during the war was: (not sure about the exact dates but this is a rough guide)
Early war (1941-1942ish) Blue Gray uppers, Light Gray lowers
Mid war (1942ish to 1944) Non specular Dark Sea Blue uppers, Non Spec. Intermediate Blue sides and Light Gray lowers.
Late war 1944 - 1945 Gloss Dark Sea Blue uppers, Insignia White lowers.
Those colors will be listed as such on the MM bottles. The FS numbers are on the site Bill listed first.