NATHAN ABERCROMBIE, ACCIDENTAL ZOMBIE, by David Lubar (Starscape/Tor 2009, 2010, etc.). In this ongoing series (currently at three books), fifth grader Nathan Abercrombie is accidentally doused with a chemical bath that leaves him partially zombie-fied...
In Book 1, MY ROTTEN LIFE, we are introduced to Nathan, the second skinniest kid in school, and the tribulations resulting therefrom. When he's doused with the chemical, he must rely on his friends, the brilliant Abigail and the occasionally-pungent Mookie, to attempt to find a cure.
In Book 2, DEAD GUY SPY, Nathan meets up with operatives of the Bureau of Useful Misadventures (BUM), a secretive organization dedicated to promoting freedom throughout the world, who attempt to recruit him due to his unique, undead abilities.
In Book 3, GOOP SOUP, Nathan and his friends must thwart the designs of an evil organization that wants to poison the water supply with fungal waste products.
In NATHAN ABERCROMBIE, Lubar has created a terrific character and series, both funny and gross (sometimes simultaneously), and always smart. Readers will be dying to hold of the next books in the series. Heh.