System Shock 2 - The Official Site - RIP May 27th 2000
This is Looking Glass Studio's Official Shock 2 site. It's a highly polished class act, and is filled with great official content, but has a more spoilers then I'd care to read. Flash 3 is required for viewing.

Irrational Games Inc -
The Irrational Games site, built by yours truly, is a sort of online brochure telling about the company and their projects, most prominently System Shock 2, of course.

Through the Looking Glass -
Though not truly an official site, I feel that it deserved to be up here. This is the mother-site to SShock2.com. Go here to learn about the other products created by the makers of System Shock 2.

Manjari's System Shock 2 Page -
A small SS2 site featuring some info on character types, psi powers, etc. The most interesting feature is the unique hand-drawn artwork on the site. Most people seem to think that SS2 and anime go well together. :)

German System Shock 2 Site -
This is a German-only Shock 2 fansite, with similar content to this one, but all in German!

Welcome To 2072 AD -
This is a small fan-site which features a collection of animated gifs and voice samples ripped from the game. Most of the gifs are taken from animated screens in the game.

Multiplayer Briefing Room -
This is a spot designed for multiplayer game coordination.

Hackmaster1's Shock 2 Page -
A small Shock 2 site featuring links and a fanfic.

Shock 2: The Divine Seeds Chronicles -
Imagine other dimensions, quantum realities, and parallel universes. What are the Divine Seeds? What are SHODAN NODES? Read part 1 of SHODAN - THE DIVINE SEED CHRONICLES and find out!

TRI.OPTIMUM -
This is a System Shock 1 & 2 fansite, under construction. At a glance, it contains maps and other goodies.

Roland's System Shock 2 site -

A fansite with some game information, a few downloads, music, cheats, and the usual assortment.

Shock2.co.uk
Another shock2 fansite, loads of content, well worth a look.

The Shock Project
A large System Shock 2 Fan Mission Pack, take a look :)