Depends on how you're defining formation. Israel is probably the most recently formed nation in that it didn't exist at all prior to 1946. However, if you are counting countries which have adopted new names (like the "Democratic Republic of Congo" during the 80's) or countries that split (czechoslovakia is now the Czech Republic and Slavakia after the fall of the U.S.S.R) there are quite a few that are "newer"
south ossetia, abkazia
[Note: the above are not nations. They are disputed regions, and are only recognized as states by a handful of nations, Russia being the chief one.]
The most recent independent nation is likely Palau, formed in 1994. Kosovo was formed in 2008, but is of disputed statehood.
Timor-Leste
Kosovo announced their independence on the 17th of February this year
Montenegro,That just separated from Serbia after the 2006 world cup!
Could it be the Hudson River? But i don't know if that's man-made.
President Musharraf of Pakistan
Namibia
The most recently formed executive department is the Department of Homeland Security. It was formed in response to the attacks of 9/11/01.
China is the most populated nation in the world.
The most recently "formed" province is Saskatchewan. It was formed by the federal government on September 1, 1905, the same day that Alberta was formed. Canada's newest province, however, is Newfoundland and Labrador, which "joined" Confederation on March 31, 1949.
department of homeland security
Nigeria is most popular black nation in the world
Africa's most populous nation is Nigeria and it is the tenth most populous nation in the world!. :)
The most advanced nation in world war 2 was probably the united states.
Spectral Type O.