Oy, why are young adult novels always the best plotlines? Not that I'm complaining, that is - my favorite book ever is a young adult novel by Peter Moore called Caught in the Act; it's about a guy who playacts his entire life who meets a mysterious gothy girl that turns his life inside out, and shows him it's okay to show his real self to the world.
The Blue Girl by Charles de Lint is another YA novel I really enjoyed. A high fantasy story about dealings with ghosts and goblins in a modern day suburban high school. (Now that I think of it, I'm not so sure it's suburban. I'll get back to you on that.)
Shakespeare, Milton, Dante, the greats from the world literature canon. I read Menea in high school, which I thought was okay (even though it was a little brutal, but I can't complain, since my favorite Shakespeare play is Titus Andronicus).
To whoever said the book 'Everything is Illuminated' was good: the movie is even better. That movie almost gave me a religious experience when I saw it in the theater, I kid you not.
And that's the dirt, mostly. Hail to all the classics-lovers out there: I am one of you!

"Be thou a spirit of health or goblin damn'd,/Bring with thee airs from heaven or blasts from hell/Be thy intents wicked or charitable,/Thou comst in such a questionable shape/That I will speak to thee."
-William Shakespeare's "Hamlet", Act I, Scene IV