So on one of my trips this summer, I went to Taos, NM for training and came across these 'earth ships'. I had never seen anything like it before and after riding by them for a couple of days, my curiosity got the best of me and so I paid the entry fee to get to check one out.
They are built into the ground, have solar panels, a grey water system, 'green house' inside and most of the building materials are from reused products. Not the most beautiful homes but whatever floats your boat eh? There was a whole community of houses and they drew a lot of curious visitors.
So before you build your dream home don't forget to look into having an earth ship!