"Pretties"--by Scott Westerfeld

I didn't want to put it down.  You definitely need to read "Uglies" first in order to understand everything in this book.  I really enjoyed how the story built on from the last book and just kept going.  I never got bored reading it and I was a little impatient about things and had trouble with wanting to know what was going to happen.  I was a really good book.  I'm so excited to read the next one!