Links

lego.com - Official lego site
LegoMindStorms - Official Mindstorms Lego site.
Lego construction site - Jennifer Clark Technic constructions - very impressive work.
Lego Robot Pages - Mark Overmars site on robotics and RCX.
RcxCC, a very good NQC implementation.
Dave Baum - Dave Baum site, THE rcx specialist.
RCX Sensor input Page - A very complete and useful site on RCX sensors.
Lugnet.com - Lego User Group NET. If you want to discover Lego community, go there !
Brickshelf.com - History of all Lego products. You can find here all the instructions of old sets.
ldraw - All the CAD softwares on Lego, using James Jessiman's standard.
Dennis Bosman - An amazing Dutch site : some incredible trucks.
Convict - A school in Luxembourg. Very interesting student's projects.
Beat Felber - A Swiss guy who present some sophisticated mining engines and some good tips. Must be seen.
Anders Gaasedal - A crane builder, at small scale, but big models.