The first book in Rick Yancey's Monstrumologist series is $1.99 today, so if you don't have it, I'd TOTALLY suggest snagging it.
If you haven't read it, DO. After all, like Arrested Development, it has such devoted and vocal fans (not to mention stellar reviews) that the series survived cancellation. (More on that here and here.)
Oh, and Artemis Fowl is $2.99 today. I almost didn't bother mentioning it, because A) I'm not a particular fan and B) it's not like the series needs a push from me, but C) I figured that since I was writing this post anyway, I may as well throw it in here, too. So there you go.
[ETA: Huh. Variant, by Robison Wells, is also $1.99. Worth a purchase? The description makes it sound like Lord of the Flies in boarding school.]