Lara Calder's "Prefab Parasite"
With humanity heading to the cities, we're going to have to get creative with our uses of urban space. Here's one idea from an Australian architect named Lara Calder: a "parasitic" house that can be attached to any vertical structure that's strong enough to support it. This design would probably run into some building code and zoning issues, but it's nothing if not creative. There are more pictures at Inhabitat.