PuppetShow is a system that allows people use there bodies to control virtual characters. Puppet show uses a webcam to track the movements of a puppet and translates the gestures into bone movements in a game engine. Puppet Show’s goal is remove confusing middleware (keyboards and mice) from the player interface and allow the users to use their body’s natural expressiveness to convey themselves in virtual environments.
http://egl.gatech.edu/puppetshow/index.htm