ANSWER
Serbia, Montenegro, Slovenia, Croatia, Bosnia-Herzegovina, and Macedonia.
The name "Yugoslavia" first came into being in 1929, when it was chosen as the new name for the former "Kingdom of Serbs, Croats and Slovenes", a kingdom formed in 1918 by a merging of Serbia and Montenegro. Modern Yugoslavia was formed at the end World War II by Josip Broz Tito, as a federation of the six republics listed above. At the end of the cold war, four of those six republics declared independence, leaving Serbia and Montenegro to form a new "Federal Republic of Yugoslavia". On February, 4, 2003, this new Yugoslavia voted to officially end "Yugoslavia" as a nation, replacing the former Federal Republic of Yugoslavia with a loose union of Serbia and Montenegro, to be called "Serbia and Montenegro".
The Yugoslav name is not completely gone from the world stage - the official name of Macedonia is "The Former Yugoslav Republic of Macedonia".
In case you were wondering about Kosovo, it was not a republic, but an autonomous province of Serbia. It is currently under the control of the UN and NATO.
WHO GOT IT RIGHT: JP Weigt, Robert Walker, Bob Milligan, Robin Campbell, Marc Quinlivan, Yanitz Grinell, Kati Williams, Jim Ahumada, Allan Christensen, and Scarlet Esho.