The simple tool above provides a low-tech bodge to help people locate missing friends and family in Christchurch following today's terrible earthquake. In every disaster, those on the outside all worry about our loved ones and those within all want to assuage the worries of their friends away.
Update: Some more tools for people in Christchurch and their loved ones:
Person Finder: Christchurch Earthquake, February 2011 (Thanks, imorgan73, via Submitterator!)
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.