Mapquest launched a useful new site "Atlas.Mapquest.com" — It's an interactive atlas, directed toward students and teachers, with tons of useful data and information — from the CIA. There's a wealth of information about populations, culture, the economy, and of course the military. There're numerous charts and photos. There's also an interesting "compare countries" feature in multiple categories like population, area, natural resources, climate, etc.
You can get information about Continents & Oceans – the land & people of the continents and find the natural resources available in the oceans, climate, languages, religions and other data on a global basis. For e.g., you can quickly discover that Mandarin Chinese is spoken by 13% of the world's population or that Buddhists constitute 6% of the world's religious populations.
More Info: Atlas