Here’s a Wars of the Roses supplement for the Lord of the Rings Strategy Battle Game. The original link has died. I’ve attached a copy below.
The Lord of the Rings Rules variants Yahoo Group has a set for Napoleonics.
Isildur’s Bane is a set of free wargames rules for playing solo games of the Lord of the Rings Battle Game.
Legends of Old Mars is a Edgar Rice Burroughs’ Barsoom variant of Games Workshop’s Lord of the Rings / Legends of the Old West game. I think that system is perfect for playing games involving John Carter, Tars Tarkas and the other denizens of Burrough’s Barsoom.
Here’s a variant of Warhammer Ancient Battles for the American Revolution. No. Really. It could work.