Eureka Miniatures offers And All For One, a set of free miniatures rules for playing swashbuckling miniatures games such as the Three Musketeers. The four page rules set is done in an interesting flow-chart style, making it very easy to follow.
“Herkybird” offers a set of medieval skirmish rules based, in part on an older rules set called Retinue.
Combat Action is a very complete universal wargames system by Fabio Fontana. He writes:
Combat Action is a strategy game of small scale conflicts. It can be used to represent skirmishes with a dozen models per side up to larger conflicts with multiple squads, vehicles and support weapons. The system presented within this book comprises two levels of detail, a simple system for small scale games where each model on the battlefield is a separate unit, and a more complex layer which adds optional rules to govern targeting, simulate chain of command and allow larger engagement of forces.
The point system will allow you to design any creature, vehicle or model you like, and field any model you create on the battlefield.
The site also has playscreens, scenarios and a complete world background.
Andy Watkins offers Hammers Slammers, a set of generic science fiction rules. Watkins has designed a lot of rules, and in each he seems to have created interesting and enjoyable rules sets.
Brimstone is a set of free wargames rules for 15mm to 28mm skirmish battles in Hell. Written by Anreas Udby, the premise is that the Prince of arkness has been slain, and that his lieutenants are battling for control of the underworld. It’s cleverly written, with lines like this:
Panic. There�s also no such thing as morale in Hell. Face it — to have morale, you really need to have such a thing as happiness. In Hell, there are really just shades of panic, hopelessness, and utter despair.
Another part I like is that it turns out that Hell has a caste system and the various denizens won’t always play nice together.
All in all, an imaginative work.