Here's a really smart LEGO build. A tiny fully motorised remote-controlled accurate version of a WWII tank by a Polish enthusiast Sariel.
It even has a motorised barrel and a rotatable turret.
The whole build is really tiny and compact. It's only 4 inches wide and 8 inches long, yet it's full of LEGO's Power Functions elements inside.
LEGO obviosuly doesn't have official WWII sets, but this would look neat as part of a larger fan-built diorama.
Here's the full clip with the tank in action:
Sariel built different motorised tanks too. Here's an American M1A2 Abrams:
Or a Russian T-72 M: