In order of greatness:
1. Imajica by Clive Barker
2. Ender's Game by Orson Scott Card
3. On the Road by Jack Kerouac
4. A Clockwork Orange by Anthony Burgess
5. Mrs. Bridge by Evan S. Connell
6. 1984 by George Orwell
7. Siddhartha by Hermann Hesse
8. Bad Haircut by Tom Perrotta
9. Fahrenheit 451 by Ray Bradbury (and I hate Ray Bradbury)
10. The Pearl by John Steinbeck
11. The Little Prince by Antoine de Saint-Exupery
12. The Lone Ranger and Tonto Fistfight in Heaven by Sherman Alexie
The following are not novels, but are well written and worth reading.
13. Flatland by Edwin A. Abbott (novel-like story narrated by a square. Borders on novel and philosophy)
14. A Walk in the Woods by Bill Bryson (memoir about two heavy-set friends hiking the Appalachian Trail)
15. Boy by Roald Dahl (funny memoir/short auto-bio of Roald Dahl, author of Matilda, The Witches, Charlie and the Chocolate Factory and scores of other fun stuff)
16. Don't Let's Go to the Dogs Tonight by Alexandra Fuller (South African problems seen from the perspective of a young girl)
17. Love That Dog by Sharon Creech (children's book in poems telling the story of a young boy who loses his dog and finds relief in writing...takes about 20 minutes to read, but will be appreciated long after)
18. Blue Rage, Black Redemption by Stanley Williams ('Tookie' auto-bio; he started a gang, ended up on death row, then worked to keep kids out of gangs, was nominated for Nobel prizes, and strove for peace between feuding gangs)
19. I'm A Stranger Here Myself by Bill Bryson (Bryson's comedic look at the indulgent life of Americans...so funny we don't care he's insulting us)
20. The Long, Hard Road Out of Hell by Marilyn Manson (auto-bio/memoir of gothic-rock artist; very intelligent, though disturbed, individual)