Both Quadrafire and Harman sell pellet stoves that can run off a 12 volt source if the grid goes down. Nice feature.

I've considered multi-fuel pellet stoves, but I could only justify the cost if it were my main heat source. I'm waiting for a model that can run off coarse wood chips, which I can produce on site.

I have not seen one of these in person but they look interesting. High-efficiency, low pollution, and no need to split wood.

http://www.greenwoodfurnace.com/

And here's a general site on wood heating

http://www.woodheat.org/

Usual disclaimers...

Steve