http://community.livejournal.com/debut2009/ -- I belong to this community of debuting authors. We're a cool group, and I highly recommend you check us out. We also have contests every month where you can win cool swag!
http://author2author.blogspot.com/ -- I love this group! It's several YA writers, all in different stages of their career/journey, and they always have such fun posts and helpful tips.
http://yawriters.blogspot.com/ -- Here's another group of authors, all from different publishers. They talk about...well, books, boys, and buzz. LOL
http://cynthialeitichsmith.blogspot.com/ -- Cynthia has a HUUUUGE wealth of info on YA. You have to read this blog!
http://rhondastapleton.blogspot.com/ -- Geeeeee, how did this one sneak in here? ROFL
http://community.livejournal.com/enchantedinkpot/ -- This blog is a group of middle-grade and YA fantasy writers. Love their posts!
http://thenovelgirls.blogspot.com/ -- another group of YA authors, doin' their thang.
http://simonpulseromanticcomedies.blogspot.com/ -- a big group of the Simon Pulse romantic comedy line authors.
http://teenfictioncafe.blogspot.com/ -- a wonderful lineup of YA authors on here!
http://yathenaeum.blogspot.com/ -- they're a group of readers and writers and do great summaries of what's happening in YA, as well as news/info/reviews, etc.
http://thefiverandoms.livejournal.com/ -- a group of great YA authors blogging.
Well, there are more I look at, of course (this list doesn't show any of the awesomesauce YA book review blogs I haunt every day--I'll do another post on those in the future), but right now I'm more interested in hearing from you. What are your favorite YA blogs, and why? I'm always looking to add to my blogroll! :D