Atlas of Urban Expansion
Global interactive map through the NYU Urban Expansion Program that is focused on mapping and measuring several key attributes of global urban expansion.
Google Earth (requires download)
Google Earth combines the power of Google Search with satellite imagery, maps, terrain and 3D buildings to put the world's geographic information at your fingertips.
This map allows you to look at any level of geography you wish including continents, countries, states and cities.
This site provides interactive maps that serve to visualize various United Nations data.