Matt Fritz has written a set of quick play rules called Day of the Dreadnaughts for recreating the Battle of Jutland. The set includes links to paper models, in case you want to try it, but don't hvae the appropriate miniatures.
Pete Pellegrino has written a set of free miniature wargames rules called Damn The Torpedos. In the game, you customize your ironclad, and then take it out to fight in the Cvil War battle of Mobile Bay.
The Civil War in 30 Minutes is a matrix game designed by Matt Fritz to help his students understand the American Civil War. If you haven't looked into matrix games, you will find that they are useful in running meaningful campaigns.
Here's a link to a set of Dr. Who miniatures rules.
Astral Dreams is a free miniatures game based on the d20 Open Gaming License system. The game's background is based on a short story of the same name, which involves a war between humans and robots.