Derived from the skew demo - http://calroc.github.com/aum-gravity/, made available in the aum-gravity github project - https://github.com/calroc/aum-gravity. The layout functionality was isolated and moved to separate files that are written as d3.layout plugins.
Interactive version on bl.ocks - /widged/4547392
Modified http://cdnjs.cloudflare.com/ajax/libs/d3/3.0.1/d3.v3.min.js to a secure url
Modified http://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.3/jquery.min.js to a secure url
https://cdnjs.cloudflare.com/ajax/libs/d3/3.0.1/d3.v3.min.js
https://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.3/jquery.min.js