WWII Platoon Commander applies the mechanics of the Blitzkrieg Commander rules to a skirmish system.
Rules: WWII
De Belli Mundi Secundus World War II DBA Variant
Damond Crump offers a WWII Variant for DBA.
Battle of Britain Rules
Battle of Britain is a set of free wargames rules for operational level games. The authors write:
This is a fast playing operational level game about the German air raids over England on August 8th, 1940. Designed for group or convention play where players are in charge of the various sectors or Luftwaffe raids and it can be completed in a few hours. This PDF includes the rules, a map, markers, cards, and aditional materials needed to play the game.
Beer and Pretzels WWII Micro Armor
GHQ has a pdf of its Beer and Pretzels WWII Micro Armor, originally a commerial set, now a set of free wargames rules.
OP Art – Operational Rules For WWII Eastern Front
Op Art is a set of rules for operational level games on the Eastern Front of WWII. The author writes:
Operational Art is the term first coined by the Russians to describe the level oc fomat that falls between the tactics used on the battlefield and the strategic direction of a war. The basic units of manoeuvre are division sized formations and the decision making level is that of army commander.
The rules have been designed so that players can recreate battles fought at this level; as a result a degree of abstraction has been included in the mechanisms used and especially in the way in which combat is resolved.