Osprey offers two free computer wallpapers.
The Miniature Wargaming Editor
Kensei Samurai Rules
Kensi is a set of free wargames rules for samurai warfare ranging from skirmishes to large battles. The rules include a fantasy element, and the world is a not-quite-historical Japan.
Valley Of The Apes Miniatures Adventure Game
Valley of the Apes is designed as an adventure game for kids. Players create their own jungle terrain, scatter the encounter tiles (with hazards or treasures) across the valley, and send bands of toy soldier figures to seek fame and riches.
Making Roads From Cork Tiles
The Wargames Table has a quick tutorial on making roads from cork tiles.
Modeling An Objective Marker
Dampf’s Modelling Page has a short description of how he created an objective marker. I really like markers like these that look like part of the landscape, as opposed to little cardboard counters or somesuch.