http://ww2drawings.jexiste.fr/Files/1-Vehicles/Allies/2-USSR/USSR-Armor.htm
This is a superb site for me. Loads of vehicles (including variants) with authentic colour schemes (including, for example, captured tanks). Will make life a lot easier for me in terms of getting an idea of colour schemes.
Examples
Here are some Russian tanks (t34 - 1943 version) and KV-1 in winter camo.
Panzer III