GestureML is the world's first markup language for multitouch and gesture-based authoring. This open XML-schema allows users to define gestures and their interactions. For more information see the examples below:

CreativeML is part of the commercial GestureWorks 3 multitouch SDK and is a part of the Open Exhibits multitouch framework. There are a number of tutorials on the GestureWorks website that explain more about GestureML.