This almost deserves its own thread.
The BioLite stove, as seen at
http://biolitestove.com/BioLite.html
It uses surplus heat from burning twigs to generate electricity to drive a fan which blows air onto the twigs causing much more efficient burning halving wood needs and massively cutting the nastier kinds of smoke, while producing surplus power for charging a mobile phone or similar device.
There's a home model for developing countries and a hiking model which is $129.
Video at
http://biolitestove.com/CampStove_Video.html