It appears to use the same underlying software as gapminder (gapminder.org). Whilst the number of
variables isn't all that large yet, the variety of ways you can manipulate the data is amazing.
For example, you can choose your variables for the x- and y-axes, and then do a time series on that
data. You can choose a country, and follow that country over time.
Excellent stuff for teaching some aspects of statistics.
See gapminder.org as well, for similar graphical displays.
Cheers
Rex