If you scroll down on the Lead Adventure thread at the link, you will find a simple set of free wargames rules and a skirmish scenario for Late Roman “Pulp” Adventure.
Miniatures Rules
Warrors of Fantasy Wargaming Rules
Warriors of Fantasy is a large scale set of fantasy rules designed to let you use any miniatures in your collection. The authors write:
�Warriors of Fantasy� is a Wargaming system that will be aimed at large scale battles using 100�s of miniatures per side. It will hopefully remain fast to play while retaining the depth of individuals. The �Warriors of Fantasy� system is geared towards representing medieval combat of all types, from realistic to high fantasy. The system is designed so you can use any figures from any manufacturer, these rules are written assuming you are using the 28mm scale (Games Workshop or equivalent). The system is designed to be rules-lite, with only about 10 or so pages of rules to learn to play.
Cthulhu Skirmish
The Cthulhu Skirmish game from Warpspawn is designed to be played on a chessboard with miniatures. Each figure represents one man or monster. I also think that it would be easily adaptable to playing as a more traditional miniatures game.
Kryomek Science Fiction Rules
Scotia Grendel now offer their classic Kryomek science fiction skirmish rules as a free download.
Coal And The Kaiser
Coal and The Kaiser is a set of “low to moderate complexity” rules for surface naval combat in the 1904 – 1918 era. The author writes:
This is a game of low to moderate complexity portraying tactical naval combat in the period from 1904 through 1918. While it will not yet you play Jutland in a day, it will let you play some fairly large actions reasonably quickly. It uses a scale of 4 minutes to the game turn and 1000 yards to an inch on the playing surface. The rules focus on big ships and big guns: battleships (and particularly the Dreadnought-type battleships that began service in 1905), battlecruisers and armored cruisers. Rules for smaller ships are meant to facilitate fast play and authentic tactics. I consider the rules to be at the beta test stage; I’ve tested them myself over a period of three years, and have started to play test them with others face to face.