Just weeks after the rise of Yo, the app that lets you send a lightweight "Yo" notification to a friend and nothing more, something more terrible has already come along. Tap is a new app for iPhone and Android that lets you send your location or a quick ping to a group of friends by simply tapping twice on your phone. The phone could be on the table, in your pocket, or on a seat in your car. The app is designed to let you quickly ping a friend when you've arrived at their house, or when dinner's ready. Notifications disappear after ten minutes.

The company calls its app "the Snapchat for location," "the world's fastest messaging app," and "four times faster than Yo." No matter what you want to call it, Tap is just the latest app trying to own your lock screen, let you send a message in an instant, or tell everybody nearby what you're up to with one tap. None of these apps are super compelling just yet, but clearly, lightweight and unique messaging experiences are here to stay. Even "glance-able" interactions like knocking on a device in your pocket also seem to be catching on. Late last year, Knock let you unlock your Mac by knocking on your iPhone. These implementations are gimmicky at best, but hint at a future where opening an app isn't the only way to reach a friend, or even to unlock your door. These apps may work like crap, but the ideas they're playing with are definitely worth chewing on.