OnMyWay has a simple goal -- it tells another person or group of people that you are currently "on your way" and sends them the estimated time of your arrival. The app sends new alerts to your contacts if your ETA changes (if you're stuck in traffic, for instance), so that you can safely continue driving and not have to call or text someone else if you're running late.
To set up a notification, the iPhone owner inputs a destination, an appointment time, and one or more phone numbers or email addresses to send alerts to, then taps the start button. iPhone contacts are integrated into the app to make setting up the notifications a snap.
OnMyWay takes care of the rest of the trip. It starts by sending an initial notification to the recipients telling them that the driver has started his trip, and then includes an estimated time of arrival. Up to three additional status messages might be sent, depending on how the driver has set up the app; if the sender is going to be late, if the person is within a pre-set number of minutes away from the destination, and when the driver is one minute from arriving.
Where I could see this app being a real boon is in letting my wife know when I'll be getting back from an appointment. If I'm running a little late, she usually pings me via text, and I have to pull over and send her a response. With OnMyWay, she'd be getting updates and would hopefully leave me to my driving... Some screenshots are in the gallery below.