I got an email about this just over a year ago and thought is was a great idea. The bit below has been taken from Wikipedia and basically explains what it is all about. If you have not got yours in your phone and you are comfortable with it all, please take a moment to add it in now.
“In case of emergency (ICE) is a programme that enables first responders, such as paramedics, firefighters, and police officers, to identify victims and contact their next of kin to obtain important medical information. The program was conceived in the mid-2000s and promoted by British paramedic Bob Brotchie in May 2005. It encourages people to enter emergency contacts in their cell phone address book under the name “ICE”. Alternately, a person can list multiple emergency contacts as “ICE1”, “ICE2″, etc. The popularity of the program has spread across Europe and Australia, and has started to grow into North America.”