The Economist World in Figures iPad edition (free) displays facts and figures for more than 190 countries around the world. Rank and compare countries, test your knowledge of country-related trivia and share fun facts via Twitter and Facebook.
A very useful app for teachers or students of economics or geopolitics, and anyone who's interested in what's going on in the world. The app also features a nice world map. There's a problem with the A-Z glossary, however, which causes the app to crash when you try to consult it.
Use the Compare tool to create bar graphs comparing data on selected topics for the countries of your choice. Great for practising numbers, figures, comparatives, superlatives, etc. The Country profiles are also a good source of data.