Brian Gills D-Day Rules are designed for 1/72 scale wargames miniatures.
Rules: WWI
Flying Circus WWI Air Rules
Flying Circus is a set of free wargames rules based on the old Avalon Hill Mustangs game.
Battle of Verdun Fast Play Rules
From the Junior General comes the Battle of Verdun Fast Play Rules. Designed for use with students, the rules are simple and fast. Paper figures also are available.
Dark World War I Rules
Dark World War is a set of free wargames rules — actually pay what you want — for playing WWI games that include demonic and mythological creatures.
Fast Play WWII Aerial Combat Rules
Matt Fritz offers a set of fast play miniatures rules for World War II Aerial Combat.