I stumbled onto this book and since I liked the title and cover, I decided to give it a read.
Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body (Vintage) by Neil Shubin impressed me. I never thought I would have the slightest interest in evolutionary biology, but the author did a stellar job of gradually walking through different biological functions and tracing back their roots. He did it in a way that made it easy for someone not strong in the biological sciences to understand.
There are chapters on hands, teeth, vision, hearing and genes. The book starts with an overview of how scientists decide where to go to recover fossils, which like a good mystery, got me hooked to read the rest of the book. I went from having almost no knowledge on evolutionary biology to understanding quite a bit. This book is a great primer into the topic.
The Colbert Report had Neil Shubin on his 1/14/2008 show.