What If?: Serious Scientific Answers to Absurd Hypothetical Questions Kindle Edition $2.99 (Reg $18)
Amazon has What If?: Serious Scientific Answers to Absurd Hypothetical Questions Kindle Edition for $2.99 (Reg $18). You can download the Kindle app for your Blackberry, iPhone, Mac, or PC here.
The book features new and never-before-answered questions, along with the most popular answers from the xkcd website. What If? is an informative feast for xkcd fans and anyone who loves to ponder the hypothetical.