Ok, these are books that I've highly antcipated reading ever since they first caught my eye, but for one reason or another have put off reading them for at least several years.
Mind: A Brief Introduction by John Searle - A book which looks at the problems relating to the understanding of the mind from a philosophical perspective. And it has Son of Man for the cover.
Zen and the Art of Motorcycle Maintenance: An Inquiry into Values by Robert Pirsig - A 17 day motorcyle trip is the framing device for a book featuring philosophical discussions over a range of issues.
Crimes Against Humanity: The Struggle for Global Justice by Geoffrey Robertson - A history of the development of international human rights law.
A Comprehensive History Of Western Ethics: What Do We Believe? by Warren Ashby - The culmination of nearly 40 years of work by Dr. Ashby.
The Holy Land by Robert Zubrin - A sci-fi satire of the Israeli/Palestinian conflict.
The Satanic Verses: A Novel by Salman Rushdie - Hard to consider yourself a humanist and not read at some point one of the most famously subversive of religious orthodoxy texts of our lives.
Collapse: How Societies Choose to Fail or Succeed by Jared Diamond - Examines how ecological factors have often contributed to the failure of societies. This is sitting on my bookshelf; considering that Diamond's previous work - Guns, Germs, and Steel - is one of my favorite non-fiction works it's pretty amazing I haven't managed to find time to read this yet.
Road to Reality: A Complete Guide to the Laws of the Universe by Roger Penrose - Also on my bookshelf. An extremely comprehensive survey of the math and physics that makes up the universe.
On the Nature of the Gods by Cicero - A skeptical look at the religions of Cicero's day, this is the work that David Hume modeled his Dialogues Concerning Natural Religion after.
The Mysterious Island by Jules Verne - A sequel of sorts to 20,000 Leagues Under the Sea. It's also already on my bookshelf.
Soul Made Flesh: The Discovery of the Brain--and How it Changed the World by Carl Zimmer - I was sold on this as soon as I saw the title. Nevermind that it's one of my favorite science writers writing about one of my favorite subjects.
In Darwin's Shadow: The Life and Science of Alfred Russel Wallace: A Biographical Study on the Psychology of History by Michael Shermer - A biographical look at the "co-discoverer" of evolution and how his personal history contributed to his subsequent pseudo-scientific beliefs.
The Girl Who Gave Birth to Rabbits: A True Medical History by Clifford Pickover - This has to be one of the strangest hoaxes ever perpetuated.
Twenty Years After by Alexandre Dumas - The sequel to The Three Musketeers, one of the best adventure books I read as a child. An on-line edition is available at the Online Literature Library, and that site also has Ten Years Later, which is the third book in the Musketeers series.