Photo Blogs
Michael Johnston's "The Online Photographer"
In my opinion, the best photo blog on the net. Mike Johnston covers everything from new products and technical stuff to to philosophy and politics. You may not always agree with him, but you'll love reading what he has to say.
Behind the Lens
Very similar to Mike Johnston's site, but with less philosophical bent. Lots of good general reflections on photography, with technical content and some very interesting images.
Daily Walks (Diane Varner)
This is a site that I visit daily (although she doesn't always post every day). Her images are simply stunning. Many are atmospheric and some are a little moody, but all are beautiful. Give yourself a little present - spend some time visiting this site.
General Photography, Instruction, and Forums
Radiant Vista
While the Radiant Vista is fairly new, it has, I believe, some of the best instructional content on the web. They do a daily critique video (taken from submitted images), a weekly Photoshop video tutorial, other photographic video tutorials, and some podcasts. And it's free (so far, anyway). There is also a "community forum" that can sometimes become lively. They just need more members. So give it a try!
Luminous Landscape
The Luminous Landscape has been around for some time. It has many hundreds of pages of useful reviews, essays, commentary, and expert advice. The primary author - Michael Reichmann - has been a photographer for a long time and has provided an excellent site. There is also a lively forum.