The Paper Toy Construction Set is a collection of jpg images of struts and girders in a variety of sizes, shapes and angles. The idea is that you print out these pieces and then use them to build your own models — much like an erector set.
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.
Mobsters Role Playing Game
Mobsters is a set of roleplaying rules for 1920s gangsters. It’s a well-done and complete game.