I know, kind of a dead topic, but I can't help myself.
I went to a college where basically all we did is read. And then read some more. And I love reading. A list of my favorites could fill pages, and the top are always in flux, but right now...
The top 5, in chronological order.
The Oedipus Cycle - Sophocles
Don Quijote - Cervantes
Treatise on Human Nature - David Hume
Beyond Good and Evil - Nietzsche
Invisible Cities - Italo Calvino