Here are a set of WWII Naval rules created by the author for playing with his homemade WWII ships.
WWII DBA is a set of free wargames rules for WWII Games based on the tried and true DBA mechanisms.
Panzerschlacht is a set of free wargames rules for WWII micro armor. The author writes:
This is the World War 2 version of AToS. It uses exactly the same game mechanisms and, apart from the weapon factors, the only difference is that the ground scale has been increased to 1mm = 1 metre to allow for more aesthetically pleasing ranges.
In our games we mark all casualties on the vehicle and figure bases. This allows a paperless game with no book-keeping whatever. By allowing the models to represent more than one vehicle it becomes possible to field an entire panzer division on an eight by six foot table.
Here’s a nice photo essay on painting WWII Russians, complete with uniform history and rank and insignia guides.
Richard Bradley has a set of WWII Coastal Warfare Rules. This is a period I’ve always wanted to play.