Designed to be a one stop portal to all material published by the USGS. Online access is provided to a wide range of USGS publications of all types (e.g. articles, maps, books, bulletins, etc.), with references to those that are not online. Continually growing in terms of numbers of publications online.

More than half of humanity now lives in cities, and the urban population is swelling by a million people each week. That concentration of people gives rise to some of the world's greatest problems, but also to its greatest innovations. Nature examines the special relationship between scientists and cities and how each can bring out the best in the other.

Wikipedia entry listing political or geological events that would change the appearance of a world map. Present back to 3150 BC. Heavy on the 20th century in terms of events and maps, but still a useful reference.