I'm sure all the other nerds know this already, but Jim Lee--he of X-Men, Batman, Superman fame--has a blog that he updates fairly regularly. I haven't bought a Jim Lee comic in a long time, but I do think he's a really good super-hero artist--and the blog is an interesting look into a comic book artist's life and work schedule. He posts a lot of sketches and works-in-progress, including, lately, video of him drawing and inking pages and sketches.
I always enjoy reading work journals of other people, especially comics folks. Until the work journals start to fill up with pictures of half-naked ladies I used to date and people pooping on things, anyway.