Trevor Brabyn has posted The Galleon and The Flame, a Sword and The Flame variant for land and naval battles in the age of Drake and Hawkins.
This is just more evidence to support my contention that — if miniature wargaming has a standard — it’s Larry Brom’s The Sword and The Flame. There are more variants of this rules set than I can count.
Colts and Arrows is a set of free wargames rules for wild west skirmishes.
Lion of the North is a set of free wargames rules for battles set in the Thirty Years War. The rules set also includes Haiduk and Rajtar for period battles in Eastern Europe, and a set of army lists.
Maurice Lite is a sampler version of Sam Mustapha’s rules for warfare in the 18th Century.
Set in the pulp 1920s, Strange Aeons is a skirmish game that sets bands of adventurers against Lovecraftian horrors. The game is commercial, but they have a free test version.