iBreath

This minuscule iCessorie plugs into your iPhone to enable totally congruous dual functionality: 1) exhale into the wand and you'll get a BAC reading on whether you're legally OK to drive, or 2) use the built-in FM transmitter to play your 'Phone's tunes through any radio, giving you something to do while sobering up, or letting you try to seduce your way out of the back of a cruiser by looping "My Milkshake".