Google's open source web app, Person Finder, is brought out in the wake of the horrific Boston Marathon tragedy. The application, which was created by Google engineers following the 2010 earthquake in Haiti, is an interface that trawls the web to aggregate data from other sites that collect info about missing persons -- like CNN, the Times, and others. The format itself, called PFIF (People Finder Interchange Format) was developed by volunteers from the Katrina People Finder Project. It lets you either input the name of someone you're looking for, or someone you have info about -- that data is then public and accessible by anyone.
The Person Finder is part of a permanent Google Crisis Response team, and is part of a suite of tools that include satellite photos, shelter locations, power outage info, and so on. When it was brought out during the 2011 Japan earthquake and tsunami, it included a way to let people to submit photos of the names listed in emergency shelters, which were then transcribed and inputted into the Person Finder.