If you're driving to a meeting and realize you're going to be late, what do you do? Pick up the phone and call ahead, right? But this means, possibly, trying to find the number for the person you're meeting with, which can be dangerous if you're in motion. And possibly illegal.
Mobile app Oops I'm Late does the calling for you. It runs on GPS-equipped Windows smartphones. If you start the app and give it access to your calendar so it knows where and when your next appointment is, it will automatically fire off text messages to the contacts in a meeting when it detects that you can't possibly make it in time. Optionally, it can also tell people how far away you are and your ETA.
The new version works with Twitter and Facebook to send both public and private messages.
There are free and paid versions. No word of iPhone support, and I have not put my hands on this product to try it. Love the idea, though.