If you can only visit one LEGO site, make it This one . Classic-space.com is where people like Dan Jassim (builder of the Dragonstar) and Keith Goldman (creator of the Iron Reich and the Ghoul) now post their MOCs. Trust me, you can learn a lot more about building from the wide variety of styles and techniques you'll find in the Classic Space forums than you will on mocpages or any one person's site.
Please excuse the current quality of my work as I'm still trying to amass a large enough collection of bricks -- I have good variety but my color coordination is still very poor. Sorry 'bout that. I promise that as soon as I have more bricks I'll get to work on MKII creations.
I have just one simple rule for posting and reviewing:
If you post a review which says something along the lines of, "I like it. EVERYBODY COME REVIEW MY MOCS!" it will be deleted as soon as I see it. This is extremely annoying.
Just so you know, I make a point of visiting the page of EVERY reviewer who DOESN'T try to plug his own creations in his posts.
I don't have "alliances" but here are some of the pages I like: Keith Goldman
If you do not know who he is, then this is probably your first visit to this site. Seriously, how does he get so many grey bricks!? Probably from your mom.
He was probably my greatest inspiration, and to this day he is the reason why I can only build one shape.
Crimso Giger to my knowledge nobody else has ever built neo-classic-space creations in the sheer variety, detail, and NUMBER that he has. Also, he can take two or three colors that clash horribly and still integrate them into a great MOC.
Matthew Rames His Plagor theme is one of the most well-developed on the site. His airspeeder designs are also worth a look.
Probably one of the most technically skilled builders on the site, he's done a lot of neat ships as well as spawning the great Variations on a Theme ... er, theme.
Shannon Ocean Where would Mocpages be without the builder from Down Under and father of the now-immortal Cyborg Race-Ship theme? Go and see it, mate!
... and I once thought Soren Roberts did the best hardsuits. I can't wait to see more of his new work now that he's branched out into microspace. Tim's, that is, not Soren's . err... both of them.
A remarkably versatile builder. He's best known for his hulking black armored vehicles, but he also does huge castles and massive armies of medieval and futurstic troops.
LegoLord 365 The DSA is one of the best "futuristic military" themes out there. The creations look both realistic and high tech, and it's amazing what this guy can do with ordinary SNOT.