A fascinating look at the most obscure realms of geometry, with some forays into physics as well. Engagingly written but perhaps a bit much for the math-phobic.
An easy read on some interesting concepts of mathematics. It uses the old book Flatland as a basis for a modern approach to more advanced mathematical concepts. It's not extremely well-written but it does explain some interesting concepts in nice analogies, making things like 10-dimensional universes easier to comprehend.