if you like techno thrillers, mike crichton's timeline and jurassic park. classics, i'd say animal farm by orwell, sir gawain and the green knight, by ??? (i have the tolkien translation) and cannery row by stienbeck.
I'm reading Dorian Gray right now, it pretty much rocks.
The Amazing Adventures of Kavalier and Clay - Michael Chabon
The Cornerstone - Randall Beth Platt
Kit's Wilderness - David Almond (anything by him really)
Sabriel/Lireal/Abhorson - Garth Nix (a great series where the antagonist is a girl (i usually don't like "girl books"), but she fights reanimated corpses and magic)
just checked home library (yay home library! even if it's small...)
tried to get ones that aren't already mentioned:
Graphic Novels- Art Spiegelman's Maus; Will Eisner's A Contract with God; Frank Miller's 300; Parjan Satrapi's Persepolis; Keiji Nakazawa's Barefoot Gen; Pascal Croci' Auschwitz
Historicals (many of above would fit here as well)- Elie Wiesel's Night; Primo Levi's Moments of Reprieve; Dee Brown's Bury My Heart at Wounded Knee
Fantasy- Christopher Paolini's Inheritance series (Eragon);Cornelia Funke's Inkspell and Inkheart; Philip Pullman's His Dark Materials trilogy (Golden Compass); Michael Ende's The Neverending Story; J.R.R. Tolkien's The Silmarillion
Books about the authors that wrote them- Alan Alda's autobiographies (Never Have Your Dog Stuffed and Things I Overheard While Talking to Myself); David Sedaris' Me Talk Pretty One Day; Hypocrite in a Poufy White Dress (couldn't find book and can't remember author)
Fiction-Gaston LeRoux's Phantom of the Opera; Louisa May Alcott's Little Women; Arthur Golden's Memoirs of a Geisha; Lowis Lowry's The Give; Dean Koontz's Odd Thomas; Mary Shelley's Frankenstein
Others i found but not enough for a whole category- Ray Bradbury's short stories (The Martian Chronicles, The Illustrated Mam, etc.); Shakespeare's Sonnets; Eve Ensler's The Vagina Monologues; Shel Silverstein's Where the Sidewalk Ends; Ambrose Bierce's The Devil's Dictionary (it actually is a dictionary, not a novel...but it's hilarious)