Superlatives

The List has quite a few "most" lists including: the wettest and driest inhabited places on Earth and the countries with the most land borders.
America's Roof has continent by continent lists of World High Points with listings of the highest point for each country.
The Extreme Science Earth Science page has information on the biggest wave and the thickest ice, among others.
See also this page of Country Rankings for a variety of population and economy statistics and this listing of the Highest, Lowest, and Deepest Points for each continent and ocean.