Ancient Combat is a set of free wargames rules by Matt Cappetta.
Guard du Corps is a set of Napoleonic miniatures rules where 1 casting = 60 combatants and one turn = 15 minutes. Basing is as per Empire.
Glave is a set of fantasy battle rules that:
can be used with any style or type of miniatures. The system uses 6 sided dice to resolve all combat outcomes. Each player gets a certain amount of “training points” to train and equip his army with.
The Starcraft Tactical Miniatures Combat rules are based on the world of the classic video game. I suppose you could use miniatures from the board game to play.
Legio Wargames offers Shieldwall, a set of free wargames rules for Dark Ages battles in the British Isles and Northern Europe.