Check out Design Feast: A metablog covering the known universe of all (OK, nearly all) domains of design. Nate Burgos has really been having fun with this site – a blog-o-blogs, there must be hundreds of new sites and ideas here to enlighten any designer. I’ll be keeping this site up in a Firefox tab as a constantly updated reference to the world of design.
(However, no direct connections to design fields of interest to me: Transformation (which may be Sustainable, but not always), Participatory design, and Dialogic design)