Modern Adaptations of Mythology for Young Adults:
The Percy Jackson and the Olympians series by Rick Riordan
The OH.MY.GODS series by Tera Lynn Childs
Eight Days of Luke by Diana Wynne Jones
Further Student Resources on Mythology:
D'Aulaires' Book of Greek Myths
D'Aulaires' Book of Norse Myths (New York Review Children's Collection Series)
The Children of Odin: The Book of Northern Myths by Padraic Colum
Heroes, Gods and Monsters of the Greek Myths by Bernard Evslin. This book is another overview of Greek Mythology and can be used in the classroom.
Mythology by Thomas Bulfinch (a modern abridgement by Edmund Fuller with a new index)