Basement Generals has a general miniature wargaming site with an extensive victorian science fiction section featuring battle reports of their Master of the World Campaign, plus photos of their figures and models.
Clauswitz’ War: Theatre-Level Napoleonic Campaign Rules is a set of free wargames rules for Napoleonic campaigns. The author writes:
These rules are designed to be used to represent theatre-level campaigning with armies of several corps per side during the Napoleonic period. Each turn is a day, and maps covering an area from 100 – 500 miles on a side with good detail (roads, rivers, towns) should be used. The intent of these rules is not to depict campaigning 100% accurately, but to provide a referee with basic guidelines for running a Kriegspiel-type game for the generation of tabletop engagements. All dice are ordinary 6-sided dice.
Gold, Swashbucklers and Pirates is a set of free rules for creating a small wargames campaign using gangs.
For those of you looking for a different setting (indeed, a different world) for your steampunk games, you could take a look at Steamworld Daleth. The author writes:
Steamworld Daleth is a gothic world on an alien planet. Call it an imaginary country, a geofiction or a follie. During the many years I have worked on Daleth (now over 20 years) the world has become what she is now: a steampunk/gothic world where the echo of the Victorian Age still sounds, but where many odd things are yet to be discovered. It’s a mix of fantasy and reality, a dreamscape of my imagination. Daleth can be used as a setting for the role playing game Intrigue & Illusions, but is not developed as such. Daleth is much more than a mere setting for a RPG. It’s a world with its own dynamics.
Day Z is a set of campaign wargame and RPG skirmish rules for games set in a zombie apocalypse. The author writes:
This DayZ ruleset is played on a simple grid map, with each grid square representing an area fifty meters on each side. The majority of towns and rural areas can be represented by a twelve-by-twelve map, though some larger areas such as Chernogorsk, Elektrozavodsk, and Solnichniy are better-suited by a double-wide, twelve-by-twenty-four map. The game starts out on the coast of Chernarus, a former Soviet republic currently experiencing a virulent outbreak of a plague rumored to originate from an island offshore of Taviana. The plague does not appear curable, and causes symptoms in its victims similar to ‘zombies’ described in popular media. Its extents are currently unknown, but it is believed to have spread across much of Europe and the Middle East.