Aberration in the Heartland of the Real: The Secret Lives of Timothy McVeigh by Wendy S. Painting.
Incredibly interesting book about the Oklahoma City bombing that is a sort of unauthorized biography of McVeigh, focusing on the vast amount of aliases, false identities and paper trails he left...
Trigonometric Delights by Eli Maor. A book that's basically about the development and important aspects of Trigonometry and its impact on science and culture.