Flutterby™! : WiFi Honk

Wi-Fi Honk intervenes before cars hit pedestrians

Other systems that have tried to do something similar have relied on dedicated short-range wireless channels that have required specialised equipment. Wi-Fi Honk relies on putting extra information into the Wi-Fi beacons about the (Android) phone's position as determined by GPS, the speed from the phone's accelerometer and direction of travel (from its gyroscope). Phones send out these beacons every 100 milliseconds by default. Wi-Fi Honk picks up signals from other devices and then uses a collision prediction algorithm to work out whether a user needs to be warned about an approaching car or pedestrian. If a collision is expected, the app automatically generates alerts that are sent to drivers and pedestrians using vibrations, sound and on-screen messages.

Time to first parent being excoriated in the press because their kid's tricycle didn't have a phone running this in 3... 2... 1 ...

Edit: Bonus: LG unveils KizON for kids’ safety:

The wearable device designed exclusively for pre-school and primary school children provides real-time location information allowing parents to monitor their children on a compatible smartphone.