I am looking for some good recreational mathematics books, on the history of mathematics, or specific topics of mathematics, interesting mathematical problems,novel ways of teaching/learning mathematics, obscure topics, etc.

My background is as a physicist, and I have two young girls who share many of my interests. I would like to find some books suitable for an intelligent and motivated student at the middle school/high school level, as well as books interesting to the educated layperson and books interesting to those with a fairly deep mathematical background.

I am currently beginning to read:

Trigonometric Delights, by Eli Maor

Other books on my list include:

Geometry Civilized: History, Culture, and Technique, by J. L. Heilbron

Pi: A Biography of the World's Most Mysterious Number

An Imaginary Tale: The Story of i [the square root of minus one]

The Pythagorean Theorem: A 4,000-Year History

And a few other similar books -- mostly on a historical angle.

I'm interested in books, also, that present interesting problems and applications, books that will engage the reader who might be wondering, "So what? Why is this important?", books that help the reader master the topic, books that might be interesting for somebody who has covered the topics years ago, and books helpful to people teaching the subject.

I'm hoping I will find a lot of math/science teachers and professionals who have excellent books in their own libraries they'd recommend.

You may check these out:

1. Fermat's Last Theorem (a.k.a. "Fermat's Enigma") by Simon Singh
2. Journey Through Genius by William Dunham
3. Euler: The Master of us All by William Dunham
4. Prime Obsession by John Derbyshire
5. Unknown Quantity by John Derbyshire
6. Math Hysteria by Ian Stewart
7. How to Cut a Cake by Ian Stewart
8. The Equation that Couldn't be Solved by Mario Livio

You can also check out the books by Martin Gardner

"God created the integers : the mathematical breakthroughs that changed history " by Stephen Hawking.

Bestselling author and physicist Stephen Hawking explores the "masterpieces" of mathematics, 25 landmarks spanning 2,500 years and representing the work of 15 mathematicians, including Augustin Cauchy, Bernard Riemann, and Alan Turing. This extensive anthology allows readers to peer into the mind of genius by providing them with excerpts from the original mathematical proofs and results. It also helps them understand the progression of mathematical thought, and the very foundations of our present-day technologies. Each chapter begins with a biography of the featured mathematician, clearly explaining the significance of the result, followed by the full proof of the work, reproduced from the original publication.

Zeno's Paradox ain't too terrible!

Edit: For reference: [Link]

Great suggestions, all!

Please keep them coming!

Although it's mainly about physics I think that The Road to Reality by Roger Penrose covers mathematics in an interesting and accessible way. His discussion about the nature of infinity was particularly engaging.

Godel, Escher, and Bach by Douglas R Hofstadter

Awesome

if you are looking for some fun mathematics, then these two books might also be relevant:

Professor Stewart's Cabinet of Mathematical Curiosities
Professor Stewart's Hoard of Mathematical Curiosities

"The Pleasures of Counting" by T.W. Körner has a nice variety of topics illustrating how maths was used to approach problems in new ways. I enjoyed reading that towards the end of my time in high school.

The Trachtenberg Speed System of Basic Mathematics - I used it often, when I was bored, while on duty in the Army (my father had taught me to multiply in mind numbers with 2 and 3 digits) but I learned only much later its name...

This one is still in print!

However, you might find it in some dark corner of your attic. I had, as a schoolboy, much fun reading that old edition.

I've read through a number of these books:

Trigonometric Delights, by Eli Maor
e: The Story of a Number, by Eli Maor
To Infinity and Beyond: A Cultural History of the Infinite, by Eli Maor (yes, his books are quite good)
(I think I may have missed one)

I am currently reading:
Unknown Quantity, by John Derbyshire

The problem is, these books have excellent bibliographies, so I've gone and bought rather a library of related books on Amazon...

This is further compounded by the fact that these books have rekindled my interest in mathematics -- I had learned it as a computational tool as a physicist, but i am now interested in relearning it properly on my own from more of a pure-math perspective, and going into topics I'd never touched on in my studies in physics.