Marcos at Topsolitario offers a set of free paper models of cargo containers for your modern and futuristic miniatures games. They are quite lovely. There’s even a video showing how to build them.
Miniatures Rules
Orion’s Gate Space Battles Game
Orion’s Gate is a one-page space battles game.
Napnuts Peninsular Campaign Rules
The Napnuts site has a set of rules for conducting a Napoleonic Peninsular campaign. The Peninsular Campaign makes for a good campaign because of its relatively limited scope.
Double Tap Spec-Ops One Page Rules
Double Tap is a set of free wargames rules for games involving special operations forces in the near future. The rules are just one page, but look as though they are anything but simplistic, as they use a reaction system.
Maxims and Mausers
Maxims and Mausers is a set of free wargames rules for European Wars from the 1870s. From the website:
Maxims and Mausers covers European Wars at the moment. Inclusion of Colonial Conflicts is planned. These are very simple rules. That may be played either as a board game on a hex map or as a miniatures game on large hexagons decorated as terrain.