Cartograms are those funky maps that provide additional information through the use of shape, distorting the geography for the sake of greater information accuracy. The canonical example is the cartogram of votes in the 2004 election: a straight map makes the "red" areas appear overwhelmingly dominant; a cartogram adding population does a much better job of showing the relative weight of urban areas.

A comment in yesterday's post on maps led me to Michael Gastner's page at the University of Michigan. Gastner links to a number of his papers on cartograms and data display, but also provides a program for the creation of your own cartograms. The source code for the latest version is here (.ZIP), while a compiled but somewhat older Windows version can be found here.

(Thanks, Ted W.)