www.nngroup.com/ : The Nielsen Norman Group (Jakob Nielsen, Donald A. Norman, Bruce "Tog" Tognazzini) has been behind a sustained drive to professionalise high tech design by defining a new kind of occupation; Interaction Design.
useit.com : Jakob Nielsen's site, principles of interaction design, events and ID community material.
asktog.com : Bruce Tognazzini's site (yet another set of design principles)