Worldmapper is a neat little tool that produces maps of the world where countries are shown in a scale proportionate to various statistics. What you see above, for instance, is the proportion of all "territory level decreases in carbon dioxide emissions between 1980 and 2000, that occurred there." That's why a few continents are missing.

Hat-tip to greenUPGRADER, who has a whole bunch of them in the post that links to.