Brandon Mull has quite a few books out there, including:
Beyonders (2 books so far, the 3rd/last will be out in 2013)
The Candy Shop Wars (2 books so far, most recent was out this year)
Pingo and Pingo and the Playground Bully (illustrated children's books, not pictured)
My boys with Brandon Mull. They had a great time meeting him and he was very kind.
Aren't signed books a beautiful thing?