Art

Art Forum
Frieze Magazine
Flash Art
Arte Contexto
SalonKritik
We make money not Art
A-Desk
e-barcelona
e-flux
YProductions
minusspace
ubu web Immense online archive of video/media art
Hamaca Media & Video Art Disrtibutors

Design/Architecture etc.

Smashing Magazine web design, graphic design
Recetas urbanas Santiago Cirugeda
Archinet

Dictionaries, Glossaries, Language resources et al.

The Getty Online Art & Architecture Thesaurus
ArtLex Online dictionary of Art Terminology
Tododiccionarios.com Collection of Art & Architecture dictionaries on-line
Visual architecture dictionary English
Visual architecture dictionary Spanish, Catalan
Urban conservation glossary English
Association of Art Editors Style Guide English

Free and Open Source Software, Copyleft, Creative Commmons & the like

Xubuntu home page
The Free Software Foundation
Dive into HTML5 Not exactly free software, but it's an entertaining and informative introduction to HTML5.

Disclaimer: I'm not responsible for any of the content on any of the websites linked to here.