The latest release of Mathematica (Version 6) has the ability to create mini-applets called Demonstrations that interactively illustrate various aspects of mathematics. The Demonstrations website has scores of free Demonstrations that can run in either the full paid version of Mathematica, or in free downloadable player (warning: 80MB download). This site is heaven for math geeks, but there’s also a mapping-related Demonstration called World Map Projections that shows how the 2D-view of the world, and individual countries, changes depending on how you project the 3D world onto a 2D surface.
Here are screenshots of the Demonstration (from the website) showing maps of the world in different projection systems:
