To go along with the previous post on Red Actions!, the free Russian Civil War rules, here is the Jackson Gamers’ RCW site. There’s plenty here to look at!
Jon Clarke has writtenUrban Myth , a set of free wargames rules set in a kind of a near future cyberpunk setting. What makes these rules stand out is in the basic die mechanism. It uses a d100 system (rolling two ten-sided dice), but you read the dice differently depending upon the difficulty level of the task:
All rolls are on d100 needing to get equal to or less than the Attribute being tested against.
How the dice are read depends on the difficulty of the test. If the action is easier it may be reduced one step or more, if harder increased one step or more.
There are three levels of difficulty for any task:
Easy: roll d100, read the dice the worst way in relation to the task (generally speaking you read the dice to fail, but if they succeed either way place the lowest dice as tens)
Normal: roll d100, identify one dice as tens & one as units before rolling.
Hard: roll d100, read the dice however you like.
Canvas Eagles is a set of free wargames rules for WWI Dogfights
The Illustrated History of the Roman Empire website is just that — a neat historical site with loads of pictures and interactive map. There is lots of fodder here for historical wargamers.