This is an example for Google I/O of the D3 visualization, with animation.
This example is live at http://bl.ocks.org/kjlubick/059355cdefeaf06d0f60e1cb2a8a4ddb
Slides from my talk are at https://docs.google.com/presentation/d/1puxW7PY2PQxOqUPyNzgBCLv_0NedlYgubtOVvqteYgk/edit#slide=id.p