If you've dreamed of living like the elves of Lothlórien, in houses high among the trees, with outdoor decks that really let you enjoy the view, you'll want to take a peek at Anthony Gibbon's Roost Treehouse designs.
The idea behind Roost Treehouse is to use shapes found in nature to create a treehouse dwelling that remains somewhat camouflaged and has little impact on the trees themselves. Only one out of each series of capsules would have a spiral staircase that goes all the way to the ground, but the capsules themselves would be joined by the deck at the top, and shorter staircases would lead from the deck into each capsule. The individual pods would sleep two people. No word on whether Gibbon plans on turning this treehouse into a reality, but he's currently working on a number of treehouse designs.