On My Way is an pretty cool Android application. When you are going somewhere, and someone is expecting you, you can use On My Way.
When you launch On My Way, you can start sharing. When you do that the application generates a url that you can share with people who are expecting you. If they access that url, they will see an embedded map that shows your current location.
It would be very cool if you could also specify your destination in the app, so then the web page could also show your ETA.