cliff-therm
Thermal Flashlight (http://publiclaboratory.org/tool/thermal-photography) built around ATMega328p on an Adafruit permaproto board (https://www.adafruit.com/products/571).
At its heart is an Arduino and a touchless thermometer which then illuminates the subject with a color based on the temperature.
I implemented the whole thing at 3.3V so that four AA batteries would run it for a good while.
Although the backlight and the lights are powered directly from Vbatt, but everything else is from a 3.3V regulator. And the processor is running on its internal 8MHz clock (valid for 3.3V operations).
It includes a nice snap-together case for the Adafruit board and an LCD and a similar battery-holder.