The Independence War Paper Models site has some very nice — and free — paper models of starships.
QSpace Hulk is a computerized version of Games Workshop’s classic miniatures-board game Space Hulk. Its designed for two people to play over the ‘net, via a network, or by email.
Here’s a treasure trove for you science fiction miniatures wargamers: The Starship Schematics Database has illustrations of hundreds of spaceships form the Star Trek, Babylon Five, Space Battleship Yamato and Battlestar Galactica universes. I think these would particularly useful as a source of illustrations for home made counters for your games.
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.
The Heavy Metal Wargaming site has some counters for use in starship games set in the Star Trek: The Next Generation universe.