Savage and Soldier magazine has a good introductory article on the US v Philippine Insurgents in the early part of the 20th Century. It’s always struck me as a period that would make for a good game.
Paper Crypt Models
The Haunted Dimensions site has paper models of three small crypts. The only downside of these is that the back of the crypts are defaced with site advertising. Still, there’s also a brick wall there that you can paste the crypts up against.
Minimal Space Combat
Minimal Space Combat is a set of free wargames rules designed to give players an introduction to wargaming and space games.
Stormed At With Shot and Shell Crimean War Miniatures Rules
Stormed At With Shot and Shell is a set of free miniatures rules for playing games set in the Crimean War. They’re designed for 15mm figures.
Charge Yr Pikes! English Civil War Rules
Charge Yr Pikes is a set of free English Civil War miniatures rules. They use a card driven turn mechanism.