Catcher in the Rye, Fahrenheit 451, and The Great Gatsby
Lord of the Flies or Private Peaceful.
So far The Outsiders, Of Mice And Men, and Hunchback.
Brave New World was by far the best assigned reading I've ever gotten. Strictly speaking, it wasn't assigned -- it was for more of a lit circle type thing, so we got to choose what book we would be assigned...
The best ACTUALLY assigned book I've ever read was 1984. :) What can I say? I'm big on dystopias.
Well.. I know my honors English class will be assigning 1984 and Brave New World.. but I already read them.. so does that count? Those are two amazing books.
Other than that, Hiroshima by John Hersey was very moving, and from back in sixth-ish grade, The Giver by Lois Lowry.
Candide by Voltaire was entertaining as well.