On the plane ride here, I was reading a long article on my Macbook Pro and instinctively touched the screen to scroll through the article. Unfortunately of course, Mac notebooks are not touchscreen (yet).
My hack, Macbook Touch overlays a "virtual touchscreen" on my Mac notebook. I've placed a Leap Motion between the keyboard and screen that tracks my fingers as they interact with the screen. I used a machine learning library, LeapTrainer, to recognize the very specific touchscreen gesture of two-finger swipe to scroll. It makes scrolling very similar to as if the Mac just had a touchscreen.
I am also in the process of adding other touchscreen features such as swipe left/right to go forward/backward.