The Warseer forums have an interesting thread on using Games Workshop’s Lord of the Rings battle game to run Warhammer 40K skirmish games.
Warhammer 40K
Making A Necron Tomb World From Packing Material
This video shows how to use basic packing inserts to make effective Necron Tombworld terrain for Warhammer 40K.
Tokens and Markers For Warhammer 40K
Rocket Ship Games has a set of tokens and markers for Warhammer 40K free for the downloading.
Fast and Dirty Sci Fi Rules
Looking for an alternative to Warhammer 40K? Who isn’t? This may be it. Even better: these wargames rules are free. Ivan Sorensen’s Fast and Dirty rules also would work for modern combat.
Expanding Space Hulk
Game Workshop’s Space Hulk game is one of the best it’s every produced. Every game is fraught with tension, as the marines attempt to maximize their scarce action points in the face of an increasing onslaught of genestealers. With good players, this game is nearly always a near run thing. Unfortunately, like so many of their efforts, the Evil Empire hasn’t continued to support it. Expanding The Hulk is a website dedicated to continuing the Space Hulk game. It’s got rules for using many of the other races in the Games Workshop universe, including Chaos, Eldar, Dark Eldar, Necrons, and Orcs.