The Gesture and Activity Recognition Toolkit (GART) (formerly Georgia Tech Gesture Toolkit) is a toolkit to allow for rapid prototyping of gesture-based applications. There are two versions of the toolkit, a Linux shell scripting based version and the more refined Java version.
A short video demo of Gesture Watch that used GART
GART Manual - includes information on the comm and vision modules, as well as the WritingPad, PinkCup, and AccelGestures examples (note that the information involving Maven is outdated)
Source code and bug tracking(trac)
Linux-Shell GT2K Home Page (older version web page - partially funcitonal)