Was playing with some EL foil (for LCD backlight), and realized you can write on the foil with a marker, and easily whipe it off again. Put in front of window or front door: "Not home burglars welcome", or a more appropriate message :-)
Now US THERE is an product that can fix your deficit! This thing takes 30mA at 1.3V, should be good for 48 hours on a rechargeable AA.
Converter is an 1V504.