Official Lego Links
LEGO® Official Website - The best construction toy in the world.

LEGO® Shop - Link to the US online store.

LEGO® Ideas - Share your creations with the rest of the world and perhaps it may become an offical set.

LEGO® Customer Service - Missing a part? Here's where to go for a replacement.

Some Other Lego Links
Brickset - The Lego set reference site.

Bricklink - The "Unofficial" Lego marketplace - need something for a project, start here.

Brickshelf - Lego Gallery Site - one of the first places where you could showcase your work.

Rebrickable - Another good Lego set reference site. - Another Lego reference site, dated format but there's some useful information there.

Lego Design - A technical Lego design reference at Rice University.

The Brick Testament - The Bible - Lego style.
Gaming Links - Creators of DOOM, Quake, RTCW and so many others. - Community site for Quake games and others. - Creators of RTCW: Enemy Territory, Quake Wars and others.

Simon "Sock" O'Callaghan - Personal website of one of the most talented game design people out there.