I read 154* books in 2006, which works out to about one every two and a half days. Since I would be awfully hard-pressed to pick a simple top ten from those I'll split it up and do ten each of fiction and non-fiction (and then ten each of the ones that disappointed me, just for good measure). Books are in no particular order within the categories, and were not necessarily published this year.
Fiction Top Ten
English Passengers by Matthew Kneale (review)
Harry Potter and the ... by J.K. Rowling (yes, I read all six this year)
The Ladies of Grace Adieu and Other Stories by Susanna Clarke (review)
Year of Wonders by Geraldine Brooks (review)
The Thirteenth Tale by Diane Setterfield (review)
The Time Traveler's Wife by Audrey Niffenegger (review)
A Conspiracy of Paper, The Coffee Trader, A Spectacle of Corruption by David Liss (I know, that's three, deal with it)
The Poe Shadow by Matthew Pearl (review)
The Seville Communion by Arturo Perez-Reverte (review)
The Alienist by Caleb Carr
Nonfiction Top Ten
Banvard's Folly by Paul Collins (review)
Team of Rivals by Doris Kearns Goodwin (review)
The Divided Ground by Alan Taylor (review)
Mayflower by Nathaniel Philbrick (review)
The Orchid Thief by Susan Orlean
Portrait of an Obsession by A.N.L. Munby
A Gentle Madness by Nicholas Basbanes (review)
The Magic Circle of Rudolf II by Peter Marshall (review)
Rough Crossings by Simon Schama (review)
Sherlock Holmes: The Unauthorized Biography by Nick Rennison (yes, it's sort of fiction, but it didn't belong in that category) (review)
Nonfiction Bottom Ten
Samuel Adams by Mark Puls (review)
1421: The Year the Chinese Discovered America by Gavin Menzies (review)
The Book of Lost Books by Stuart Kelly (review)
Nathaniel's Nutmeg by Giles Milton
What Would the Founders Do? by Richard Brookhiser (review)
Dark Bargain by Larry Goldstone (review)
One Good Turn by Witold Rybczynski
Dante by Barbara Reynolds (review)
Walking to Canterbury by Jerry Ellis
Patriotic Treason by Evan Carton (review)
Fiction Bottom Ten
The Keep by Jennifer Egan
The Collectors by David Baldacci (review)
The Book of Fate by Brad Meltzer (review)
The Third Translation by Matthew Bondurant (review)
Lost by Gregory Maguire
Malefice by Leslie Wilson
The Master by Colm Toibin
The Queen of the South by Arturo Perez-Reverte
The Death of Colonel Mann by Cynthia Peale
Death of an Ugly Stepsister by Gregory Maguire
*At least. As I wrote this post I kept finding more that I had forgotten.