Fubar is a good looking one page set of modern and science fiction rules.
Rules: Science Fiction
Free 3D Terrain For Dust Tactics
Top Solitario, one of my favorite sites for its quality free paper products, has a selection of 3-D terrain pieces for Dust and other games which can be downloaded, printed and quickly constructed — a bonus is that they also fold flat!
Aquazone Game of Deep Sea Exploration and Combat
Aqua Zone is a set of free wargames rules for playing miniatures games that feature underwater combat with submarines, DSV’s and marine animals.
Faction Wars Science Fiction Skirmish
Fire and Forget Games has released a downloadable PDF version of the rules for Faction Wars, the sci-fi skirmish game. The free 40-page PDF contains the basic rules of the game, sample squads for two factions, and a couple of scenarios to get you started.
Mobile Suit (MS) Era Rules
MS Era is a set of free wargames rules for playing with those Mobile Suit Gundam figurines.