Mobile phone & gadget charging stations for flood incident deployment (car battery in a box with lots of USB outputs), maybe a wifi hotspot?
Using switching regulator to control & step down the 12VDC car battery to a lot of 5V USB-A sockets. Appropriate regulator part here: http://www.onsemi.com/pub_link/Collateral/MC34063A-D.PDF
There is an interesting discussion here: http://electronics.stackexchange.com/questions/31037/building-a-usb-charger-for-camping