You know, the iPad isn't the only type of tablet out there. Wacom has been making high-quality tablet input devices for artists for years now, and their latest, the Intuos 4, cuts its cables to go completely wireless.
The Intuos 4 lets you use a pen to draw or write on your computer. It talks to your computer using Bluetooth, and charges up via USB. It's also newly extra-sensitive to pressure, making it much easier to make light strokes when your pen is barely touching the surface. Look for it to drop in a few weeks for $400.