In volunteering at IdeaCity this past week, I heard a alk from Francis Gendron about Earthship Biotecture. In essence, these sustainably built homes rely on recycled tires, the earth surrounding the land, strategic alignment with the yearly sun, ingenious airflow for natural heating and cooling, and supremely efficient water usage to make them some of the most beautiful and efficient homes I've heard about to date! More specifics here:
Earthship has internships, a full Academy to learn how to build, and a variety of e-books and online videos to learn how to build in this earth friendly way. I think my favourite talk of the three days.