Div, Grad, Curl, and All That: An Informal Text on Vector Calculus, 4th Edition, by H. M. Schey.
Amazon
W. W. Norton
Books a Million
This gives an engineer's take on vector calculus. It is very well written. If you are taking an E&M course, I highly recommend having this book on hand.
Calculus On Manifolds: A Modern Approach To Classical Theorems Of Advanced Calculus, 5th Edition, by Michael Spivak.
This book gives a more abstract approach to doing calculus on curved surfaces. A manifold is just a term for spaces that can be curved. I recommend this book for highly motivated students of mathematics.