Aaron surprised us all by not talking about wind power, voltaics etc but going to the heart of a more sustainable house - PLACE. It is how you set a building up in a place and what you make it out of that has the most impact.
Our own house is set facing south with major wind breaks on the north and seasonal shade on the south. The Palmers did a fantastic job of locating the building in the best possible place.
In our next home we will go as far as we can to use the principles that Aaron talks about here - all are common sense and all will save you money.