The Dark Realm is a set of free miniatures rules for Dark Realm’s line of 6mm science fiction games.
Germy’s World has some nice paper models for 6mm science fiction gaming. There are tanks, drop pods, a mega drop pod and a drop ship. These would be useful for Battletech, or Reaper’s CAV, or Games Workshop’s Epic 40K.
Germ’s World has a large collection of paper models for wargames in 6mm scale. These would be useful for, say a BattleTech game, or maybe Epic 40k. There are hangars, moon bases, factories, space docks and middle east buildings.
Squirmydad has a tutorial on converting 25mm paper figures to 6mm paper figures suitable for mounting on pennies. He superimposes the original figures on a colored circle that can be folded and glued to pennies. Using Photoshop, he shows you how to adjust the DPI, scale, and add the background and base. It’s very good, and I’m going to try the same thing in Corel PhotoPaint.
The 6mm Wargaming site is a nice general site on the scale.