KiddieDial is a simple but effective app that could potentially save your life. Depending on how old your children are, they may not be able to dial multiple numbers or use a phone. But they probably do know how to play with cell phones, games in particular. With KiddieDial, you can pre program a phone number that will dial when the app is pressed.
Kids these days love playing with all the gadgets their parents have. So it would be fairly easy to tell them to press on the ambulance icon if something happens to Mom or Dad.
Get it for 99 cents from BlackBerry World.