In plastic...ooo boy
Plains Wars (sioux-cheyenne-7'th cavalry)
Zulu Wars (sorry dont like the existing plastic range)
Aztecan Wars (painterschallenge i would say)
Greek-Persian Wars (immortal games is going to do that in plastic propably)
The Baron's Wars (early medieval)
American War Of Independance ( would be nice compatible with french indian wars)
i'm going to stop because...