Up until now, your smartphone could practically do anything you would want it to do. But wouldn’t it be great if it could tell you that you’ve had too many drinks to get behind the wheel? Thanks to the power of crowdfunding, we now have the Breathometer. This little guy can strap onto your keychain and go with you for a night out on the town. Just plug it into your headphone jack of your iPhone or Android device, and fire up the app to give you your BAC levels.

Buy now: $20+ USD