Roofs that hold water: reduce heating and cooling costs, increase life of roof, and create a rooftop garden! Would be great on a shipping container home, as there might be a risk of collapsed roof otherwise if drainage isn't sufficient.
Sky Garden House by Guz Architects. Wierd, but I think it would be really nice to inhabit. It's also an interesting application of green roofs/roof gardens to a very modern, otherwise steel and concrete design.