You can control Gnome 3 desktop just by waving your hands in the air. Igalia has developed a technology called Skeltrack which is a Free and Open Source Software library to provide easy to use human skeleton tracking. Here is a video of controlling Gnome 3 using this technology and hand gestures.

This demo is, as usual, Free Software so you can grab the code from GitHub and tweak it to do what you want to do with it.