I used the large Kensington Turbomouse trackball for 16+ years. I’ve seen some cool mice and other devices but always gone back to that big trackball because:
(1) I could go to any location on a screen without having to lift my hand,
(2) It stayed in one place (especially important for keyboard trays), and
(3) The four buttons were programmable, letting me do more without having to change to the keyboard.
Well I took half a look at the Apple Magic Trackpad and knew I finally found my trackball replacement. It’s a 4.25″ by 5″ conductive metal pad that runs on batteries and connects via bluetooth. Combined with Lion, the Trackpad allows you to gesture. With one finger it behaves like a mouse. With two fingers it scrolls. Not only can you pinch with two fingers to zoom, you can pinch with four fingers (think thumb, no pinky) to call up Launchpad, a collection of all of your applications.
Unlike the iPad, these gestures are not completely supported for all applications. For example, Safari will zoom in/out via gesture but Firefox will not. I’m holding my breath for a track pinch-zoom in ProTools, not found in version 10. Yet.
I can’t seem to program any custom gestures, but it’s so intuitive and quick I don’t really care. If you find yourself near an Apple Store, check out the Magic Trackpad. It lives up to the name.