Bob Cordery offers Redcoats and Natives, a set of free wargames rules for the colonial period.
rules
Panzer Troops WWII Rules
Panzer Troops is a set of free wargames rules for WWII battles. The rules are intended as an introduction to historical wargaming.
SAGA Isengard Battleboard
A Saga battleboard and army list for the forces of Isengard from the Lord of the Rings.
Pike and Shot Rules
John Armatys offers a set of Pike and Shot rules for fighting large, multi-player English Civil War battles.
Two Page Lego Minifigs Rules Set
Consortium Games offers Minifigz, a two page rules set for battles with Lego minifigs, and similar mini people. I’m going to have to give this a try.
Update: The original link is dead. You can still find Minifigz on the Wayback Machine.