http://www.greenhomesforsale.com/
An interesting alternative Real Estate site. Worth browsing just to see what others are building. Samples:
(http://www.greenhomesforsale.com/media/17761_8_thumb.JPG) a house in Hawaii.
(http://www.greenhomesforsale.com/media/17600_6_thumb.jpg) a NC home with energy-efficient mortgage.