One thing that I love about YA authors is that so many of them have blogs on which they interact with their readers. Here's a couple of my personal favorites. Feel free to share your own in the comments.
Elizabeth Scott: Not only does she had a great blog that she posts on at least three times a week, but she runs a contest for her readers every week for great new YA novels! Great fun to read and participate in.
Andrea Cremer: A great new author who's already used to blogging, Andrea Cremer is great in her blog posts. If you haven't yet heard of Nightshade go check it out. The book was a good read!
Nina Malkin: Though she doesn't post much, when she does, it's well worth reading. Nina Malkin is hysterical yet honest in her talks about characters and plot, and her blog is great reading!