Today I also worked on what I'm calling the Tether drawing program (first version here). I cut it down to one tether, but I have that tether rotating in a circle. This is all controlled with the Leap: vertical and horizontal finger position determines where the line is drawn to, finger depth (towards the screen) determines stroke weight, and the more fingers you draw with, the faster the tether rotates.
Here's a video and some images:
