[bobsy]

As someone with poor circulaton to the extremities I fear I would be walking around in the dark holding the flash light with cold hands.

Its a really nice idea though. Its stories like this that make me wish i paid a bit more attention in science when i was younger.

[koudelka]

If your extremities' temperature is cooler than the ambient temperature, maybe all you need is a version with the heat-collection plates flipped?

[schiffern]

If your extremities' temperature is cooler than the ambient temperature, how did you do that? Heat pumps in your arms? ;)

It would be trivial to put some circuitry in there to rectify the voltage so it works in either direction. No separate version required.

(changing ambient temperature is the obvious answer to my joke, btw)