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.
Richard Bradley has a set of WWII Coastal Warfare Rules. This is a period I’ve always wanted to play.
Mage Knight Kevin has a nice photo tutorial on painting US paratroopers from WWII.