The Ancestor's Tale by Richard Dawkins. 2004, ISBN 0-618-00583-8.
This is a fantastic book. I loved reading it. (The entry on wikipedia contains a lot of information about the book.) Highly recommended for those interested in learning something about how various living things are related. Since this is a non-fiction science book, information contained in it will change a bit as new discoveries are made, still much of the information is well establish, so this book should be a good introduction to evolution for the layman for many years to come.
Purchased new from the PSU bookstore on 2-23-2005 for $28.

Climbing Mount Improbable by Richard Dawkins. 1996, ISBN 978-0-393-31682-7. This book is about the Theory of Evolution or Darwin's idea of Natural Selection. It discusses how generations of individuals are more or less successful at passing their genes on to succeeding generations thus 'selecting' some genes while others are de-selected. This process is impersonal and not directed by anything, it is just the result of the actions of the environment on a population over a period of time. This author discusses how something which seems to be improbable could over many thousand of generations be slowly perfected (to its current observed state.) Excellent book, worth reading more than once. Purchased at Powell's 9-9-2011 for $7.98.