These are my personal favourites. Students as young as thirteen may enjoy them, but most of them will appeal more to those who are 14+, and some should be saved until later.
You can find short descriptions of them on my Booklist (PDF). Amazon.com will also provide good descriptions and reviews by other readers.
Lorraine Hansberry, A Raisin in the Sun
Aldous Huxley, Brave New World
Harper Lee, To Kill a Mockingbird
Alan Paton, Cry, the Beloved Country
Erich Maria Remarque, All Quiet on the Western Front
Mary Renault, The King Must Die
Gabrielle Roy, The Road Past Altamont
J.D. Salinger, The Catcher in the Rye
Alexander Solshenitsyn, One Day in the Life of Ivan Denisovich