The Fast Play Rules for the Seven Years War. The author writes:
These are fast play rules for mid-18th century battles with 15 mm figures, the focus is on playability. They are ideal for campaingnplay, where you would want to finish the battle in one or maximum two hours. They are not suited for historical refights.
Germ’s World has a two sets of paper corridors for use as terrain with your wargames: a set of dungeon corridors and a set for science fiction. The sets include wall sections of various lengths, crossroads, junctions, staircases, archways, pits, traps and more. They are easily as good as many of the commercially available sets. You could use these for any number of games, including Games Workshop’s Space Hulk or Warhammer Quest, WizKids’ MageKnight Dungeons, or just a regular Dungeons and Dragons slaughterfest.
Bob Cordery offers Redcoats and Natives, a set of free wargames rules for the colonial period.
Panzer Troops is a set of free wargames rules for WWII battles. The rules are intended as an introduction to historical wargaming.
A Saga battleboard and army list for the forces of Isengard from the Lord of the Rings.