When the world is in crisis—as it is after today's earthquake and tsunami in Japan—we turn to Google. After the earthquake in Haiti, Google formed a crisis response team that produces tools that anyone can use in a time of calamity. Right now, Google's main search page is displaying a tsunami warning. The search engine's Person Finder is also currently live for Japan —you can tell friends and family that you are okay and those searching for someone can post a query. The tool was enormously valuable during the New Zealand earthquake. The Google pages also have emergency numbers and maps of shelters and medical clinics.
There are also some worthwhile apps for iPhones in times of S.H.T.F. The Pocket First Aid & CPR app was developed with the American Heart Association. It helped save a man's life during the Haiti earthquake: Trapped in a building for two days, he used it to treat a fracture and cope with symptoms of shock. Close Call is a simple, useful app that displays emergency information about you (allergies, etc.) on your phone's lock screen. Several apps exist that will e-mail your GPS location to emergency services and emergency contacts, but they have poor ratings and complaints of bugginess. Here I Am is the most basic and well-reviewed. An emergency radio app could come in handy.
If today's events have you really on edge, you can load up your phone with survivalist apps. The venerable SAS Survival Guide will teach you how to light fires, navigate by the stars, gather salt and water, and the like. The wikiHow site has a free app that will help you deliver babies, deal with snakebites, and scare away bears. But almost all of these guides start with the same piece of advice: If you have the time and the means, call for help. The most valuable lifesaving feature of the phone is the phone.