Oh, another thing that's fun to do, at least on a desktop machine where you have a regular mouse, is to use Active Screen Corners (under System Preferences -> Dashboard & Expose). I set mine up so if I touch the top left corner of the screen with the mouse pointer, it uses Expose to show all of the open windows. I also have the top right show the screensaver so I can just flick the mouse when I walk away from the machine, bottom right show the Dashboard, and bottom left hide all the open windows for easy access to the desktop. I'm not sure how well that would work with the trackpad, though.