Wolfram Alpha is one of the best online sources for up-to-date, authoritative data, especially statistics about countries and cultures.
e.g., type in "wealth <country name>" or "poverty <country name>" or "debt <country name>" or "infant mortality <country name>" or "per capita income <country name>"
Some widgets are shown on this page as an example, but feel free to enter your own queries or create your own widgets.
Gapminder is a website that provides both data and tools to look at the world. See Gapminder Data.
Gapminder Documentation describes the methods, sources and data used to produce the various datasets of gapminder. The data itself is available through excel files.
Worldmapper is a collection of world maps, where territories are re-sized on each map according to the subject of interest.
There are now nearly 700 maps. Links to source data for each map are provided.
This ongoing project is a collaboration between professors at the University of Sheffield (UK) and the University of Michigan (USA).
Danny Dorling, University of Sheffield
Danny has done much work in the development of cartograms and human cartography, and was responsible for devising this project, and the huge task of gathering all of the required data together. He leads the Social and Spatial Inequalities research group, in the Geography Department at the University of Sheffield.
The Atlas of the Real World by 
