Often when it's the most crucial to get in touch with family and friends, our phone service fails us. Local family-safety and "emergency network" company Life360 has answered that need — more than 1,600 Japanese families used the app to reunite after Friday's devastating earthquake. Life360 tells you the location of up to 6 family members when they "check in" or press the "panic" button.

While the panic button is to be used during times of emergency (it tells people exactly where you are and that you're in trouble), the "check in" feature is more for tab-keeping (say, if someone's traveling internationally and you want to make sure they've gotten to their destinations safely).  Both alerts automatically send an email, text and phone call to loved ones in your network.

Co-founder and CEO Chris Hulls got the idea for Life360 after seeing how many families were turned upside down by Hurricane Katrina due to a lack of preparation and resources.  The (free) application now has more than 2,000,000 downloads (TechCrunch reported recently on their surge), won first place in the Google Android Developer Challenge in 2008 and was a Facebook fbFund Technology Winner in 2009. They launched on iPhones in the fall of 2010.  

In an area that's as—hate to say it—earthquake-prone as the Bay Area, it's a worthy download for future emergencies.