I love the licence plate as roofing material, the artisanal fences, bone door handles and reclaimed materials construction that Dan discusses. Save landfill and money.
Recycled building materials are not always acceptable for every building project, however, I find the prospect and art of building with salvaged materials invigorating and fun. I love the idea of shipping container housing, my workshed (where I am typing this) is a recycled materials building. You might think less about the recycled materials house, and its ok if you point and laugh, as long as you take a look.