Manorhouse Workshop has a set of three tutorials on making wargames terrain from high density polystyrene (insulation board).
Corvus Ancient Naval Rules
Corvus is a set of free wargames rules for fighting ancient sea battles.
Dinosaur Cowboys
Dinosaur Cowboys is a set of role playing / miniatures rules that reminds me of the old comic Cadillacs and Dinosaurs. It looks like a lot of fun.
The Sword In The 20th Century
The Sword In The 20th Century is a variant of Larry Brom’s classic The Sword and The Flame colonial rules.
Rifle and Kepi 19th Century Rules
Martin Rapier offers Rifle and Kepi, a set of free wargames rules for large scale battles of the 19th Century.