Since the bombing i always register as in case of an emergency they can contact you or your loved ones back home.
It is free and takes 2 working days to get through.All it takes is a couple of minutes to fill out online.I have just done mine again.
It does work as when we were in Thailand and the tsunami came through, they contacted our emergency contact back home.
Alot of people are not aware that you can and should do this and alot of people worry a little when so called new warnings come through.
http://www.smarttraveller.gov.au/
Cheers
Tuberose.