As one who prefers the keyboard to the mouse, I'm always interested in changes to the Mac operating system that make the keyboard usable in more places. One such change was snuck into Exposé with the Snow Leopard update.
After activating Exposé in All Windows mode (F9, or the dedicated key on your keyboard), you can now select windows by typing portions of their names (as shown below each window). Depending on the names of the open windows, you can select a window with as little as one keystroke, though it will usually take two or three to uniquely identify a window.
As you type, the system will move the blue halo to the currently-selected window. When you see that the window you want to switch to is highlighted, just press Return to exit Exposé; that window will appear in the foreground.
This simple change means I can now easily use Exposé without ever touching the mouse. (In OS X 10.5, you can select windows in Exposé's All Windows mode using the arrow keys, but with more than a few windows open, this quickly becomes time consuming.) Thanks to Mac OS X Hints reader PhilHints for uncovering this timesaving tip.