This is a concept for a neat, electricity-free automatic door system that uses mechanical energy provided by your footfalls. It's still in the concept stages so the door material is soft, but perhaps with a little nanotech this will become feasible in future.
The first 00:56 of this video shows how the mechanism works; fast forward to 00:57 if you just want to see the door in action.
We like the little "ssshk" sound effect that's a by-product of the mechanics.
The concept is by UK-based design student Wai Man Cheung. You can peep his other stuff on Coroflot.