Check out this great TidBITS article listing some "hidden refinements" in Snow Leopard. In particular, scroll down to the Exposé Shortcuts section. In addition to the features I list in the book, you can press Command-1 within an Exposé window display to sort the windows by name, and Command-2 to sort them by application. Plus, you can hover the mouse over a window and then press Space to get a larger (Quick Look) view of the window! Exposé is so much more useful in Snow Leopard than it has ever been before...

—Posted by Matt Neuburg on August 28, 2009