Someone asked about a stove-top fan in this thread. In addition to
the thermo-electric fan that is fairly popular with wood stove
enthusiasts, there is a wood stove fan - the Heat Wave - that is
based on 200 year old technology - the Stirling engine - which
efficiently converts heat energy directly to mechanical. I got one
in December of '05 and love it - although it is a bit on the pricy
side - ~$170 - I got mine for $150 in December. It comes with a
lifetime warranty. Contact info is below.
If you are interested in some of the research that is going on with
this external combustion engine, just google Stirling engine and
you'll be kept busy for a while. As an example, research done at
Sandia Nat'l Lab in Albuquerque, NM with two electrical generating
companies in California and a manufacturing company in Arizona is
being applied to creating a 1 GW production facility in California.
The basic unit is a Stirling engine with the hot end sitting at the
focal point of a parabolic mirror about the size of an old satellite
TV dish. The array will consist of a large number of these units.
Another example is a unit planned by a New Zealand company that
contains a Stirling engine in an appliance unit about the size of a
kitchen dishwasher. It burns natural gas and supplies both
electricity and heat for a complete household.