I've got an iPad on the way when the 3G's come out at the end of this month. Unfortunately, it's for work only. This usage may qualify as grounds for dismissal. But this is pretty cool, albeit a bit unpractical.
Sprocket Pocket App gives you the pattern to make a pocket for your iPad on the back of a jacker. Lean forward, you get the forward arrow. Lean left or right and you get a turn signal. Sit up and you'll see the stop sign. Not bad!
iPad Sprocket Pocket from MAYAnMAYA on Vimeo.