The Lightning Thief by Rick Riordan
Percy Jackson doesn't exactly have the makings of a hero. He's ADHD, dyslexic, and has never lasted an entire year at any school. He's not bad - chaos just seems to erupt around him.
But at his most recent school, a boarding facility for troubled youth, things are a little weirder than usual. Any school year when your math teacher tries to kill you on a class field trip qualifies as a little out of the ordinary. Then, Percy discovers that his best friend, Grover, is a satyr, that his Latin teacher is a centaur, and that he has to leave school immediately for the safe haven of Camp Half-Blood.
Because Percy is a demigod, the bastard son of Poseidon, and not a few Furies, hell hounds, and major deities want him dead.
At Camp Half-Blood, Percy meets the children of Dionysus, Athena, and all of Ares's horrible, violent little brats. But his time there is fairly short, because bad things are stirring on Mount Olympus that could lead to all-out celestial warfare. And though he's only just come into his powers, and barely understands them, Percy is sent out with Grover and Annabeth, one of Athena's daughters, to save humanity and the heavens.
The story of a young chosen hero, his two best friends, a brainy girl and a doofy boy, sent off on a quest to save the world and defeat great evil may sound a little familiar. However, The Lightning Thief owes more to Neil Gaiman than to J.K. Rowling, kind of an American Gods for the preteen set. But while it's a bit derivative, it's very funny, very exciting, and very well-written. The Lightning Thief has a distinctive, fresh voice that will appeal to Rowling fans, and never feels like a rip-off.
This is the first in the Percy Jackson and the Olympians series. The second and third titles, The Sea of Monsters and The Titan's Curse were released in 2006 and this May, respectively.