Another Perl article over at IBM DeveloperWorks titled "Create geographical plots of your data using Perl, GD, and plot-latlong":

"Using world and custom U.S. maps, Perl, GD, and the Cooperative Association for Internet Data Analysis (CAIDA) plot-latlong tool, this article demonstrates how to create your own effective data visualizations in the spirit of Google maps and the U.S. national atlas."

As always with IBM DeveloperWorks articles, there is a feedback form at the end of the article.

Martin