When is an iPhone not an iPhone? When it's a spirit-level, of course; at least, that's the latest way to repurpose your $399+ wunderphone. Photographer Ben Long was seemingly staging a ghetto photoshoot but lacked a level to make sure his camera was straight. Thankfully he'd had the foresight to Jailbreak his iPhone, load iLevel - which taps into the iPhone's accelerometer - and slapped that on the back of the Canon to get the shot balanced.
Now, admittedly, this wasn't really an impromptu hack. Ben had already Jailbroken his iPhone, but I'm not sure whether he'd installed iLevel previously or whether he had to go trawling through Installer.app on the off chance that someone had saved him a few bucks with a spirit-level program. However, it's nifty and useful and it might come in handy in the future for you, so I'm writing about it.
I think it may be very useful in some situations :)