Yo. What seemed like something that was just too simple to actually be practical, the Yo app has grown to over 1 million users and tons of press. The app lets you send a message to your friends who use it. All you do is tap their name and they get the message “Yo.” It seems useless considering this is just slightly easier than sending a text with the same content, right? Well, today’s update to Yo adds a few updated features that makes it even more useful.

There is a new feature called Yo Index, which allows you to receive automatic Yo updates in conjunction with other services. For example, you can sign up to receive a Yo message when your package arrives from FedEx or when your Citi Bike rack runs out of bikes (as well as when one is returned there). Anyone is able to submit a feature for index meaning the possibilities are endless. It looks like a way to streamline notifications and receive them for just about anything via one single app. This feature seems to hold a lot more possibilities and usefulness than just being able to say, “Yo” to your friends.

What Sparks our Fire: An app evolving to become both useful and impressively effective.

What would you like Yo notifications for?