After being robbed at gunpoint in his home, Seth Froom realised that even in the Land of the Free, where homeowners can keep guns, you can't keep a gun on you at all times.
So, on the basis that you normally have your iPhone to hand, he's come up with Yellow Jacket – an iPhone case that turns your iPhone 4 or 4S into a 650,000V stun gun, just like James Bond's phone in Tomorrow Never Dies.
Okay, asethetically the Yellow Jacket isn't going to win any awards – but then, it is packing a whopping great power source for the stun gun. That adds three-eighths of an inch and 4oz of bulk to your iPhone, though on the plus side it also gives you an extra 20 hours of battery life. That comes from the same battery that powers the stun gun, though – so you'll have to choose between another couple of hours of juice or the ability to zap an assailant.
Since you carry your phone right next to your face, the Yellow Jacket also has a couple of safety features – a safety catch and a rotating electrode-cap to prevent misfires.
Obviously if you're in the UK the Yellow Jacket's a no-no – stun guns are illegal in Britain. But if you're in the US, it's currently touting for funding on Indiegogo – the case will retail for US$125, but you can pick one up as an Early Bird special offer for US$85, in black, white or a rather fetching pink.