Christopher L. Bennett. Christopher just started his blog this weekend, and his thoughtful rambles are definitely worth checking out.
Kurt Busiek. One of the finest comics writers ever, and also a swell guy to boot, this is one of the more entertaining blogs around because it's just full of cool stuff.
Peter David. The first coming of me, the self-styled writer of stuff was made for blogging, as anyone who's read his "But I Digress..." column has known for decades. Always a fun fun read.
Rhonda Eudaly. One of the four redheads of the apocalypse, this wonderful Texas writer is a good egg and a fine writer and you should read her stuff right now.
Neil Gaiman. Just today I realized that next year, I'll have known Neil for 20 years. He was the hottest new comics writer out of Britain at the time, and I was a young editor at Library Journal and a freelance reviewer/journalist in the genre field. We're both a lot more successful now, but I still want to be him when I grow up. Always a joy to read.
Robert Greenberger. Of all the professional writers/editors I've known over the years, I've known Bob the longest, dating back to a correspondence he and I and drewshi shared back in college. Bob has remained a very good friend and colleague, and his blog is a wonderful source of info about a working writer/editor, about local Connecticut politics, about popular culture, about being a Mets fan, and other stuff.
Martin Pasko. Marty's one of those guys who I'm stunned that he considers me a colleague, 'cause I'm just some shmo and he's Marty fucking Pasko. He doesn't update nearly often enough, but when he does, it's stuff you should read.
John Scalzi. The blog that actually earned John a best fan writer Hugo nomination, mainly by the power of its tremendous awesomeness. One of the best blogs out there, honestly.
Mark Waid. BOOM! Studios editor-in-chief and comics writer extraordinaire, and also a great guy and a total comics geek, Mark's entire blog is worth it just for "Great Moments in Comics."
If there's a writer blog that isn't here (and isn't on LJ) that you think I should be reading, let me know in the comments......