The Book Thief by Markus Zusak Told by death itself, this is the story of a brave and thoughtful little girl living in Nazi Germany during WWII. Heartbreaking and beautiful.
The House of the Scorpion by Nancy Farmer. A great piece of young adult dystopian fiction, involving cloning, drug lords, and the disappearance of the whales.
The Once and Future King by T.H. White. A whimsical and enjoyable retelling of the King Arthur saga.
The Percy Jackson Series by Rick Riordan. I linked to my review of the first book, The Lightning Thief, but all five were excellent. A brilliant way to bring classical mythology to life, and to envision it coexisting with today's modern life.
As I Lay Dying by William Faulkner. I'm glad I gave Faulkner another shot, because I loved this bit of dark comedy.
House of Sand and Fog by Andre Dubus III. A tragic and beautiful story about people too caught up in themselves to understand one another.
Animal Farm by George Orwell. Perhaps the perfect allegory, this famous work shows beautifully what happens when socialism goes awry.
Into Thin Air by Jon Krakauer. A riveting account of an expedition to climb Mount Everest gone horribly wrong.
Cat's Eye by Margaret Atwood. This book could be the model for today's "Mean Girls" phenomenon. A great story that examines girls'--and womens'--relationships with one another.
The Curious Incident of the Dog in the Night-time by Mark Haddon. Told in one of the most unique voices, this book chronicles a brilliant but autistic teen's attempt to solve a mystery.
And the honorable mentions: