Google Earth gets my vote for application of the decade. You can almost consider throwing away your atlases as Google Earth offers you the chance to move around and zoom in on anywhere on the Earth. The technology feels about 4 years ahead of its time. Free of charge you can download it here (now avaliable for Macs too).
And after browsing around a while I managed to find these interesting places (need Google Earth to run):
Area 51, USA.
Top Secret Saudi Arabian Airbase.
Wau Namus Caldera, Libya.
Lakehurst AirBase, USA.
City of God Favela, Rio, Brazil.
Monument Valley, USA.
It is weird being able to look at some of these places that you’re not supposed to know exist, and some people may put this information to a bad use, but overall I think this is an amazing learning tool I wish I had as a youngster.