Without a dedicated shutter button on the iPhone, taking photos requires you to press the touchscreen, which is hardly an intuitive option. Some Aussie developers have launched a camera app that instead uses sound as the shutter's trigger.
Called Soundsnap, the app lets you use any sound, be it your voice or the snap f your fingers, to trigger the camera's shutter, which is especially useful if you happen to have your camera mounted on a tripod. Even better is the fact that you can use a Bluetooth headset to remotely trigger the shutter from across the room, without having to shout like a fool to get the app to work.
The app costs $1.19 from the iTunes Store.