Some of you may remember I Crayon Physics a while back. This is a new physics sandbox called Phun that let's you experiment with physics in a playful environment. You draw the environment, tweak the physical properties, and then watch the results in real time. Phun includes motors and liquids as well as hinges and friction controls. Just like Crayon Physics, this is a great application for pen and finger inputs. Download a beta of this and give it a run on your UMPC at let us know what you think.