General Art Sites
Digital Blasphemy - A semi-subscription site with wallpapers and links to other sites.
Gallery of Vickimess - Awesome abstract works. Beware of pop-ups!
The Internet Eye - Full of news and reviews, plus tutorials on various programs.
Prism Break - Very clean, crisp art. My favorites are the "mundane" images such as maps on a desk.
Surreal Places - Very realistic renderings of real and imaginary cities.
While you were asleep - One of my absolute favorite artists! This site serves as an inspiration for me to keep working at my skills.