This site bills itself as "massive central data source and a handy way
to graphically compare nations." They have more than 4,000 data sets,
and they specialize in tools that let users easily compare data from
different countries. As one would expect, they offer a large amount of
economic data and they present it in a variety of ways (including maps).
Perhaps it is best to have them describe their breadth: "We want to be
the web's one-stop resource for country statistics on everything
from soldiers to wall plug voltages." It is a very interesting site
to browse through as well.