Invisible City Games offers a free board game called Aliens vs Cows. The aliens try to abduct cows. The cows try to protect the planet from the invasion.
How big is a Stardestroyer compared to a Romulan D’deridex? Which is bigger, a Vorlon cruiser, or Farscape’s Moya? This great site has size comparisons of the great ships from science fiction.
Here are some rules for using the Dirtside II system to recreate battles from Heinlein’s Starship Troopers.
The Heavy Metal Wargaming site has some counters for use in starship games set in the Star Trek: The Next Generation universe.
Ty Beard’s Fistfull of Tripods is a set of free wargames rules for fighting battles from H.G. Wells’ War of the Worlds. It is a tactical level game, where one stand is a platoon. I’ts designed for 1/300 (6mm) scale figures.
NOTE: This is an updated URL. The old one was no longer working.