A little bit about Matt...
He's the Geography Guide for About.com, the Internet's leading News and Information service. (http://geography.about.com) There, he writes weekly articles about geography, provides annotated links to hundreds of the best Internet sites for geography, hosts regular chats, moderates an online forum, and answers tons of email. Matt is also the author of "The Handy Geography Answer Book."

County Information
The Country Studies / Area Handbooks from the Library of Congress are fantastic, they provide book-length information about 100 countries around the world. They're detailed, exhaustive, and, most importantly, searchable.

Maps
ExpediaMaps' Place Finder includes a wonderful database of place names - from the smallest towns in Russia to the streets of New York City. It's where I go to find the location of anywhere and to obtain a great map!

Population Data
The U.S. Census Bureau's IDB Summary Demographic Data database is frequently updated with population estimates and projections for every country. It also includes such facts as birth and death rate and historical population data. It's awesome.

Climate
WorldClimate offers average temperatures, precipitation, and even elevation for even the most remote weather stations around the world.

Flags
A country's flag and the flag's history says a lot about that place. Flags of the World is a amazing site that provides images of contemporary and historic flags for countries, states, and even wanna-be countries.

Time
The title of World Timezone Map says it all - this site displays the current time in each time zone around the world. It's a great reference.