No Man Knows My History: The Life of Joseph Smith by Fawn M. Brodie. Originally written in 1945 and still one of the better American biographies. Yes, Mormonism, like all other major religions is based on a fairy tail.
The definitive book according to Jon Krakauer.
I'm currently reading:
Under the Banner of Heaven
Reefer Madness : Sex, Drugs, and Cheap Labor in the American Black Market by Eric Schlosser
Until I Find You : by John Irving
and Mind Game by the BP Crew.