GeoHive: Global Statistics
Global Statistics is a collection of tables and graphs providing a statistical look at countries, their population, area, capital, main cities, etc.
www.geohive.com/   reviews

Guinness World Records
www.guinnessworldrecords.com/   reviews

City Population - the largest cities in the world
City Population: the principal cities and agglomerations of the world and of many countries (tables and maps).
www.citypopulation.de/   reviews