Here are some links to places that I find to be very useful or just plain old fun.

Some cool Photoshop site:
Top 40 Photoshop Experts by Greg Vander Houwen
Digital Mastery by Ben Willmore
Photoshop Techiques Forum

If you like animation, and who doesn't, try these:
Rustboy truely some amazing work by one person.
Bill Plympton, what can you say. He's the master.
Victor Navone, one cool dude working at Pixar shares his stuff.