I just saw this Mathnasium blog post and it made me want to pass it on. If you love to read, read to your kids, or just want to pass on the love of reading, and have an interest in math, then this post is a great resource. It points to a lot of great books that integrate math into reading for kids in different age groups.
Do you have any books you think should be added to the list?
One challenging mathy book that I read in High School comes to mind: "Godel Escher Bach, An Eternal Golden Braid" by Douglas Hofstadter. That book is fascinating and complex as it explores ideas in math, art and music in superbly creative ways.
Another book that comes to mind is "The Phantom Tollbooth" by Norton Juster. A classic of children's literature, it is a great read aloud book with a similarly exploratory mindset.
I'm sure there are many more good books to recommend. Sometime I'll put together my list of great math movies...