From the mother and daughter team that brought you Lionboy comes Halo, an enormously involving story in which a young girl is castaway on an island full of centaurs. She must dress as a boy to survive, and ends up in the centre of Athenian politics. It's a wonderfully original take on ancient myth, and Halo is a lively and intelligent heroine battling to find out about herself within the context of greater turmoil.
(The cover, by the way, shouldn't have been in Greek letters - the title reads EDLTH. Confusing for a book that has the Greek alphabet in the back.)