I just recently stumbled across this series, and I wish I had earlier. Every book is addicting. Ally Carter's other books, Heist Society and Uncommon Criminals, are pretty good too. It's junior fiction, but I believe that's the best kind :)
The Gone series is a weird one for sure. I recommend more for young adults or people who enjoy young adult books. I for one didn't put the book down until I finished it. They are also a bit of a longer read than other young adult books.
The Uglies Series - Gotta finish this series. I was halfway though Specials and started moving. Never picked it back up again. UPDATE- Tally Youngblood is Katniss' equal. And Scott Westerfeld writes the BEST female characters.