Professional Links
International Interior Design Association - has an "Especially for the Public" section
American Society of Interior Designers (ASID)
California Council for Interior Design Certification - good consumers' guide
Simon Bucktrout - graphic design
Resolve Digital - web design and marketing
U.S. Green Building Council - non-profit working to make green buildings available to everyone

Inspirational
Bang-Olufsen - cool tools & such
Bulthaup - euro kitchens
Design Within Reach - classic modern and contemporary furniture
Limn - art and furniture
Modern Furniture Classics - a great collection of modern masters
New Leaf Gallery - garden sculpture
Sothebys - antiques, art and real estate around the world

Especially Informational
Designing Your Space - ASID's Guide to Interior Design (PDF)