http://d3js.org/

http://www.ourd3js.com/wordpress/?p=51
http://www.ourd3js.com/wordpress/?p=104
file:///D:/test/d3/test.html

http://bost.ocks.org/mike/join/

https://github.com/mbostock/d3/wiki/SVG-Shapes
http://www.w3.org/TR/SVG/shapes.html#CircleElement

http://bl.ocks.org/mbostock/3808218
http://bl.ocks.org/mbostock/5779690