Janet Reid, Literary Agent - snarky, in a fun way. Very knowledgeable. Especially helpful with information on queries and the business end of things.
Query Shark - this is Janet Reid again, but dedicated only to query letters. A lot of fun and very informative.
Cockeyed Caravan - by Matt Bird -
Story Doctor by David Farland
By C.C. Finlay - Ok, so I just found this site and I'm adding it here until I have time to look it over. But it's from the editor of Fantasy and Science Fiction, for crying out loud, so I've gotta be checking it out. So do you!
Also, since I'm currently focused on trying to writer for Cracked.com, it makes sense that I'd check out the blog of their head honcho - David Wong. Ah, darn, looks like he's still getting it set up. I'll have to come back and look at it later.