This is pretty cool. Gizmodo has a short article and video showing you how you can use your iPhone 3GS as a camera for your iPad. You put the Camera-A app ($0.99) on your iPad and the Camera-B app (free) on your iPhone. Then, via a Bluetooth connection, anything that your iPhone camera points at appears on your iPad screen. There's a button on the bottom of the iPad screen that you can touch to take a photo.