BitcoinVisualizer by John Russell.
From the webpage:
Block Viewer visualizes the Bitcoin block chain by building an ownership network on top of the underlying transaction network and presents a web-enabled user interface to display the visualization results.
Great mapping exercise!
Imagine what could be done tracking all banking transfers.
Before you object that banking transfer monitoring would require a search warrant, remember that Richard Nixon could not be prosecuted for treason because the evidence was the result of an illegal wiretap.
Take this mapping as a reminder to use cash whenever possible.
Demo: http://www.blockviewer.com/#30203900
I first saw this in a tweet by Max De Marzi.