The BACtrack Mobile Breathalyzer is the first such device that connects to your iPhone using bluetooth. You use it like any other breathalyzer, but the kicker here is that it sends the BAC (blood alcohol content) reading to your iPhone. The app then tells you exactly when your BAC will come back down to zero. It also helps you share the BAC with others. Be warned that social media postings made while you’re sloshed are often cause for embarrassment the next morning.