Very cool! I created a small bookmarklet that injects it into the system we're developing over here. It's nice to amaze some colleagues real quick. ;)

    javascript:(function(){var%20s=document.createElement('script');s.setAttribute('src','https://raw.github.com/franzenzenhofer/box2d-jquery/master/js/lib/jquery.box2d.min.js');document.getElementsByTagName('body')[0].appendChild(s);window.setTimeout(function(){$("#main-nav,header").box2d({'y-velocity':5,'x-velocity':-0.05,'debug':false});},500);})();

Note: if you copy this in the omnibox of chrome, you will need to re-add "javascript:" in front of it.

Edit: And a working bookmarklet for HN that also injects jquery.

    javascript:(function(){var%20s=document.createElement('script');s.setAttribute('src','//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js');document.getElementsByTagName('body')[0].appendChild(s);s=document.createElement('script');s.setAttribute('src','https://raw.github.com/franzenzenhofer/box2d-jquery/master/js/lib/jquery.box2d.min.js');document.getElementsByTagName('body')[0].appendChild(s);window.setTimeout(function(){$("td:first()").box2d({'y-velocity':5,'x-velocity':-0.05,'debug':false});},500);})();