Internet resources
Appendix C of the book lists a number of useful LEGO websites (both official and unofficial). You can access those same links and some additional ones here.
General resources
Brickshelf
Peeron LEGO Inventories
Brickset
The Unofficial LEGO MINDSTORMS NXT Book Repository
NXT Programs: Fun Projects for your LEGO MINDSTORMS NXT
MINDSTORMS NXT Building Instructions
Technica
Programming resources
Programming Solutions for the LEGO MINDSTORMS NXT: Which approach is best for you?
Bluetooth resources
MINDSTORMS Bluetooth Resources
NXT Bluetooth Compatibility List (no longer available)
Analysis of the NXT Bluetooth-Communication Protocol
NXT blogs
The Unofficial LEGO MINDSTORMS NXT Inventor's Guide Companion Blog
bNXT (no longer available)
LEGO computer-aided design resources
Google SketchUp NXT Parts Library
Tutorial: Setting up LDraw to Create Virtual NXT Robots
Building techniques
LEGO Education Constructopedia
Sergei Egorov’s LEGO Geartrains
Educational resources
FIRST LEGO League
US FIRST Curriculum Collection
LEGO sets, LEGO pieces, and custom hardware
LEGO storage
Storage and Organizers at the LEGO Education Store
Personal websites
Dave Astolfo
Daniele Benedettelli
Bryan Bonahoom (no longer available)