Lee Byron has released his source code to create Streamgraphs under the open source BSD license.
A streamgraph is a novel way to represent data when a traditional stacked graph doesn't suffice.
Byron created a steamgraph for the New York Times in 2008 to represent move box office receipts from 1986 to 2008.
As a Last.fm user, Byron made a streamgraph to represent what music he has been listened to.
Byron's code is a Java applet and the target audience is people who know how to program.
You can learn more about streamgraphs by reading his white paper.