Global Map Projector
NASA’s Global Map Projector — G.Projector for short — is a lovely little program that transforms any equirectangular map image (one is included) into another projection. It’s a tremendous amount of fun, and a very useful way of visualizing map projections. It’s a Java application, so there are some performance issues, but at least it’s cross-platform (so long as you have Java installed).
A library of compatible map images is available here.
Thanks to Paul B. Anderson, who’s responsible for this excellent map projections site, for the links.