http://gizmodo.com/5526462/incredible-perching-uav-lands-on-and-takes-off-from-walls
That's pretty great.
They mention it's "bat or insect-like". In fact, I see this as being more like a bird. I see small birds do this same kind of thing where they cling to a wall with their feet. I think it's awesome how robotics uses nature to these kinds of effects.