Oldie, but goodie from Benhard Jenny, Tom Patterson, and Lorenz Hurni – Flex Projector–Interactive Software for Designing World Map Projections get the freeware on the Flex Projector website.
I am always looking for ways to show staff how projections really impact our work in GIS. This is a very nice example of this. Azavea.com put together 8 projections, all at the same scale with the same center – not surprisingly show that change.
Click on each to see the projection legend. So what is the correct projection? Well that depends on what you are doing with the data! Check out the USGS publication “Map Projections – A Working Manual” overview on Plate 1.