NXT Programs - site provides free building instructions and downloadable programs for lots of fun projects.
Inanimate Reason - Robots, RC, Sailing, ARG, and every combination thereof! Includes Lego Mindstorms unofficial upgrade kits for NXT 1.0 to 2.0 and 2.0 to 1.0
HiTechnic Products - they manufactures a range of robotic sensors for the LEGO® MINDSTORMS® NXT. The majority of HiTechnic sensors are certified by The LEGO Company assuring the highest standards of quality and safety.
Bricker - This resource was developed to give users information about LEGO and LEGO compatible construction toys. Here you might find: set prices; set reviews; parts and minifigures; and hot news;
Sean Kenny - LEGO® Architecture models
BrickBlogger - LEGO Architecture – Ancient World Civilizations