About a year, year-and-a-half ago, Deviant Artist Dirk Loechel created one heck of a sci-fi spaceship size comparison chart. It's great to check in on Loechel's fixes and updates every once in awhile. I particularly like the fact that he mixes ships from TV, movies, and video games. There's Mass Effect and Star Trek, Halo and Robotech, Starfox and Stargate...the list goes on forever. I'm continually drawn to the EVE Online ships (you can find them front and center; one of them is that ship that looks like an apple core). For heaven's sake, though, can some Deviant Artist please hook him up with a higher resolution Independence Day mothership?
Some recent additions include ships from Dune, Transformers, The Hitchhiker's Guide to the Galaxy, X3, Freelancer, and many more. It's nuts.