Here I have a list of links from various sites I like. I recommend them all. :-)
Tech Sites:
Mike Wong's "I want you for the Galactic Empire" site
Very cool site with loads of material on Star Trek, Star Wars, and even some additional essays relating to science. Even if you're not into vs. debating, his essays are a very good read, and very insightful into various scientific fields such as thermodynamics.
Babtech On The Net by Brian Young (currently offline)
The BEST Babylon-5 tech site. Sticks to canon, makes fair judgements, and best of all, does not get molded by the desires of the vs. debating community for bigger numbers. Better than that OTHER B5 tech site which shall remain nameless, and no one can convince me otherwise.
Brian Young's Turbolaser Commentaries
Gives good insights into the workings of the turbolasers found in Star Wars. Did I mention they're not really lasers? :-)
Star Wars Technical Commentaries by Curtis Saxton
The site that started it all. Gives tons of info on various issues of the fictional Star Wars universe.
The Ultimate Star Wars vs. Star Trek Database by Wayne Poe
Not as high on my list as the others. For one thing, Wayne Poe and I haven't had the nicest of histories. Another is that it's not actually a "tech" site like the others: it's purpose is not to analyze but to house the various Trek vs. Wars arguments that have raged over the years, mostly at alt.startrek.vs.starwars, and really to show how stupid some Trekkies are. Still, I recommend "Borg vs. Empire": it had me in tears I was laughing so hard.
3D Art and Animation Sites:
Where it all began for me. Johan Alm is a masterful 3D artist, making very cool movies of Star Wars, Star Trek, Babylon-5, and Battlestar Galactica fighting it out. Sadly, he's retired from the hobby, but his site is still up.
3DFrontier: Spacebattles Forum
Currently, only the Spacebattles forums are on 3D Frontier, but eventually it will become a web community much like 3D Gladiators is and Sci-Fi Art once was.
A group of professional and amateur 3D artists, with very good artwork, and a large online community dedicated to art. I lurk at their forums and post sometimes, since I'm a moderator in the Agoraphobia subboard.
BattleTech:
Before I ever cracked open a BTech novel, this place let me in on everything that's happened in the BTech universe. A very well-done and comprehensive site on the rich BattleTech universe.
This site has a lot of info on the equipment of BattleTech, ranging from the great Clan McKenna-class battleships to the smallest Inner Sphere 'Mech. A must read for anyone getting into BTech, or trying to write BTech fanfiction like me. :-)
This site is even more comprehensive than the Technical Archives in terms of equipment from the Field Manuals and readouts. In addition, they have a comprehensive listing of the units for many of the factions of the BattleTech universe.
The only BTech-orientated forums I frequent. Discussion can get slow at times, but the posters are pretty good people and it can get interesting how many spins and POVs people can have on a fictional universe as diverse as BattleTech. Watch out for the Clanners: they bite!
Miscellaneous:
This web forum specializes in RPG-style games (Story Debates if you're a Spacebattler, TGODs if you're an ASVSer) and has many going on right now, including the modern "Destiny of the World", an Age of Imperialism era game, a post-apocalyptic future one, an alternate timeline WWII-era one, and my favorite (and the only one I'm participating in), the BTech Shattered Sphere.
An online archive of the US Navy's ships since WWII, giving details on the history of their design, specifics of the design, and a list of the ships of it's class. I love this place.
Mr. T is helluva tough, foo'! And this site is dedicated to pic fanfics of him knocking the crap out of everyone from Neo and Morpheus from The Matrix, Darth Maul, Worf, Duke Nukem, and even the Borg. :-)
Proof that the humanity isn't all it's cracked up to be. Some people can be absolute idiots. Have fun busting a gut at people who use CD-ROM drives as cupholders. :-D