As a career writer, I depend on publishing blogs for information. And most of the publishing blogs where I get my information are written by literary agents.
I also receive a lot of e-mails from readers and fans who want to get into publishing with their own writing, and I'm always offering links to my favorite blogs, where I think they can get the best advice. This advice is free; you don't have to pay for it.
The blogs I always advise potential writers to stay away from are the blogs that focus more on rejection than publication, with snarky blog posts about the awful queries they receive on a daily basis. They can be funny at first, but it gets tired. And, they are usually anonymous bloggers, which makes them pointless and insignificant. I'm also not a huge fan of the "best friend" agent bloggers. These are the agent bloggers who have an agenda they are trying to push with blogging; they aren't doing it just for fun and to help writers. They are usually younger agents, without many big books, and they tend to create more hype than writers need to know. They also attract a huge, almost cult-like following, of people who don't have the slightest clue about what the publishing industry is all about. And I find that the comments on "best friend" agents blogs can often be harmful to new writers.
Below is a short list of my daily publishing blog habits. I don't link to them on my sidebar, but I do read them daily to keep informed. And if you are seeking publication, or plan to seek publication in the future, I don't think you can go wrong with any of these blogs. And I'm not listing them in any specific order: I think they all do equally well in keeping writers informed.
http://bookendslitagency.blogspot.com/ This one covers it all. It's never snarky and there's always something to learn.
http://pubrants.blogspot.com/ This one is practical, with industry news that is always objective and informative. And, it gets into some of the more technical areas of publishing, with regards to contracts and other important things writers should know. I learned what "in perpetuity" was from this blog. And, she's a nicest person on the Internet.
http://jetreidliterary.blogspot.com/ You'll find a great deal about querying agents and what to avoid while querying agents on this blog. And, you'll get a good laugh, too. Though she can be a bit abrasive at times, she balances it out, always, with posts about how much she loves her work. And I never feel as if I'm being treated poorly there, and I always feel as if she's the best writers' advocate on the web.
http://lyonsliterary.blogspot.com/ This is a smart blog, written by a brilliant man. He hasn't posted anything in a while, but it's worth checking out to see what he'll post next, and also to read previous posts. I've been his fan for a long time and I don't think he knows how many fans he really has, which makes his blog even nicer to read.
http://agentinthemiddle.blogspot.com/ This is blog is simple, to the point, and if you're interested in horror, erotic romance, or anything along the lines of erotica, it's probably one of the few agents blogs where you can get information about the genre. She also is a huge fan of lgbt books, and she has over twenty years of agenting experience under her belt.
http://askaliteraryagent.blogspot.com/ He doesn't post daily. But he is, to me, the God of literary agents. Every single post is worth reading if you are serious about getting published. His own published book "The First Five Pages," helped me more than any publishing book out there.
http://dglm.blogspot.com/ I like these guys because there's no BS. It's real, it's informative, and there are no bells and whistles. And, the books they've sold speak for themselves. They don't have to have bells and whistles, their professional track record is all they need.
http://arcaedia.livejournal.com/ This one is a *must* for new writers. You'll learn more about querying agents here than anywhere else on the web. And it's done very well.
There are a few others that I didn't mention, but that's only because I don't have time to read them all on a daily basis. So check out the blogs above and see what you think. And try to avoid the "best friend" agent blogs if you can. Over a period of time, if you are a new writer, they can do more harm than good.