A Splendid Victory is a set of free wargames rules for the English Civil War. They’re designed for 28mm figures, but the basing system is flexible.
Miniatures Rules
Pigs and Glory: The Viking Sagas
Pigs and Glory is a set of free wargames rules for Viking Saga Campaigns. It is designed to give some context to period battles.
1862 Campaign Rules
1862 is a set of American Civil War Campaign Rules designed for Johnny Reb, but which could be used with any miniatures rules set.
Quick Play Low Intensity Warfare Campaign Rules
Quick Play Low Intensity is a set of free wargames rules for playing campaigns set in Vietnam or similar conflicts.
Late Medieval Skirmish Rules
The Late Medieval Skirmish Rules is a set of free wargames rules for large scale figures on an actual dining room table (with salt shakers, etc.)