Oh god haha, I just invisioned a world war II themed texture pack.
Creepers would be the japanese, because of their Kamikaze runs.
Zombies would be the national socialists because they hold their arms up, even though the national socialist salute doesn't use both arms.
Pigs would be french for obvious reasons.
Endermen could be the U.S., because we didn't get involved until we were "looked at".
Not sure about the rest. We should totally make this as a collaboration project though.