The massive earthquake in Japan was a perfect example. Power was cut for millions of people, which meant that TVs and radios were useless for getting emergency instructions. And phone lines were overwhelmed by people trying to call each other. To keep the lines available for emergency crews, the Japanese carriers placed restrictions on 80% of the voice traffic. When most people tried to call, the lines were dead.

That's why smartphones are so useful during an emergency. They have their own batteries, and they have Internet connections that function even when phone service is interrupted. Best of all, smartphones have smart apps that can give you lifesaving capabilities.

Here are the very best smartphone apps for emergency events:

. The free BuddyGuard app from MPOWER Labs is now available for iOS devices and will soon ship for and BlackBerry as well, according to the company. Think of BuddyGuard as a smart "panic button."

By clicking on the big button on the app, your camera will start taking pictures every ten seconds. All sounds are recorded constantly, and your GPS location is captured every three seconds. All this data is uploaded every 30 seconds to the , and a link to that data is broadcast to your list of emergency contacts.