I know I've said this already but if you're not reading A Newbie's Guide to Publishing, then you're really missing out on a great education in writing and publishing. Even if you're not interesting in self-publishing, there are a lot of great tips for how to market your book, both in the posts AND in the comments.
I've been paying more attention to the comments lately because the blog's host, Joe Konrath, has been letting a series of guests post of the blog, each sharing their path to publication, or their thoughts on publishing in general. There's one author who's made a nuisance out of himself in the comments (just my opinion), whining about how his books aren't selling. The other commenters basically told him that it's a crap shoot and to focus on writing the next book, but the author didn't really want to hear it, preferring to keep obsessing over what was wrong with this book. I sympathize a little because I have a tendency to obsess over things I can't control either, but I try not to inflict my neuroses on other people either.
What struck me in particular was that the author had published four or five other books that were successful and he was getting hung up on the sales of his latest book. I've published two stories so far, with a third (!) being available for pre-order at the end of November. I can understand being disappointed in sales, especially if you want to make a living from your writing, but there really isn't time to mope about it. With publishers releasing new books every week, the best way to deal with disappointment from your last book is to write another one. That's one lesson from the blog post comments I can definitely take to heart.