This is probably the coolest bit of iOS connectivity I've seen so far. KL Dartboard is an iPad app serving as a virtual dartboard for darts thrown by an iPhone app, called KL Darts. Basically you buy the iPad app and lean it up to the wall, and then you download the free iPhone app and connect them using Bluetooth, Once the setup is complete, the angle that you hold and/or shake the iPhone determines where the darts hit on the iPad's board.
The iPhone app requires OS 4, you've got to have both devices, and the reviews state that it doesn't work very well. It's impossible for the iPad to know "where" the iPhone is, so you there really is no need to face the screen to throw the darts correctly.
It is only a matter of time before your iPhone slips from your fingers and flys into the your iPad. DOH
iPhone version is FREE, but the iPad Dart App will run you $4 from Apple iTunes Store