Here are a few books that I've read over the years that I've enjoyed.

Keith Devlin

• The Language of Mathematics: Making the Invisible Visible - A wonderful book, a sorta of "finishing course" to high school mathematics. This is where I started.
• Thinking Mathmatically - An introductory course on the basics of thinking like a mathematician.

Charles Seife

• Zero: The Biography of a Dangerous Idea - the first book I recommended to budding numerists.
• Proofiness: How You're Being Fooled by the Numbers

Giovanni Vignale

• The Beautiful Invisible: Creativity, Imagination, and Theoretical Physics

David Orrell

• Truth or Beauty: Science and the Quest for Order - Very readable. Questioning aesthetics of what we want to find rather that way is actually there.

John D. Barrow

• The Infinite Book: A Short Guide to the Boundless, Timeless and Endless
• The Constants of Nature: The Numbers That Encode the Deepest Secrets of the Universe
• The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe
• The Origin Of The Universe: Science Masters Series

Peter Atkins

• Galileo's Finger: The Ten Great Ideas of Science - Creepy title. Great read.
• Four Laws That Drive the Universe - a very approachable primer on the four laws of thermodynamics.

Charles G. Fraser

• Half-Hours with Great Scientists: The Story of Physics - In my opinion, a true classic. Very hard to find.

Robert Kaplan

• The Nothing that Is: A Natural History of Zero

Stephen Hawking

• A Brief History of Time - from the Big Bang to Black Holes
• Black Holes and Baby Universes and Other Essays
• The Universe in a Nutshell

Brian Shul

• Sled Driver: Flying the World's Fastest Jet - I never tire of reading this. This one is also very hard to find, and quite expensive.

Ben Rich & Leo Janos

• Skunk Works: A Personal Memoir of My Years at Lockheed

Paul Crickmore

• Lockheed SR-71, Secret Missions Exposed