When I was a kid, I remember reading and loving E.T. Bell's "Men of Mathematics". I later learned that his scholarship leaves something to be desired, but he brought out the humanity and genius of the big names and famous characters of mathematics. Bellos doesn't have a similar goal in "Alex's Adventures in Numberland", as he's just as interested in applications and the quirky patterns of maths as he is in the people behind it, but he captured my interest the way no writer since E.T. Bell has. You should read this book.

I normally collect the Good Bits from books in my reviews, but I'm not going to do that this time: you should buy or borrow it, read it, and enjoy it.