A masonry fireplace for your house
When I first learned about masonry fireplaces (also called Russian fireplaces), it was a mystery to me why more houses don't have them; it still is. Actually, I've never seen one in the flesh (or stone or brick). But I think unless you are a thermostat junkie, masonry fireplaces are the best way to heat a home along with some passive solar.
The way a masonry fireplace works is you build a hot fire in the firebox. The hot air heats the bricks or stones through a series of twists and turns that it has to go through before going out the chimney. Because the fire is very hot it completely burns your wood so there is no creosote build up and the air that finally leaves the chimney has very few polluting particles in it. The fire burns for about and hour or two and the heat radiates out from the bricks or stones up to 24 hours.
It is possible to build it yourself, but you will have to buy the bricks. These can't be adobe or mud, because of the high temperatures. I think stone would be pretty difficult. This guy has a lot of information about building it yourself, although it is a little hard to follow at times. Some Mother Earth articles here and here. Another guy that did it himself. Then there is the European style with soapstone, really beautiful; I would like to be able to use soapstone for other applications also (if I win the lottery). These appear to be kits that you build yourself. Here's some good info from the brick industry. And then there is the Masonry Heater Association.