The World Factbook - I recently discovered this single webpage which allows you  access to the demographics and all of the details of every country in the world. Just select the country that interests you and with one click, up it comes. This is a great aid for schoolkids and young and mature age students alike. This site is a free service and is updated regularly and it also has links to to reference maps, flags of the world and a guide to a country's profiles. Not only great for new knowledge but can settle lots of debates about what's what and who's who.