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.
This would be awesome suspended from the tree in place of a treehouse! Quoted from the official website: “It's a tent. it's a bouncy castle. it's a swing. it's a trampoline! Welcome to the wonderful world of Treepee! This looks so fun!