Just wanted to add a few holidays from my adopted/other home country, the Czech Republic (in case of updates to this sticky).
May 8: end of the Prague Uprising, 1945 (and the day before the Red Army rolled in)
July 5: celebrates Saints Cyril and Metoděje, who arrived in the Czech Republic as missionaries around 860 AD and are credited with creating the Slavonic alphabet and language
July 6: commemorates when philosopher and reformer Jan Hus was burned at the stake in the 15th century
September 28: Saint Wenceslas' Day / Czech Statehood Day
October 28: creation of the Czechoslovak state, 1918
November 17: commemorates the student uprising of 1939 and the student uprising on the same day fifty years later (which sparked the Velvet Revolution).
December 5: Saint Nicholas ("Mikuláš," in Czech) Day (On this day, Saint Nicholas--accompanied by a devil and an angel, or at least teenagers dressed up like them--visits children and reads from a book of names, identifying good and bad children. Good children get chocolate. Bad children do not. Teenagers love the holiday because they get paid to roam around the city dressed as Saint Nicholas, an angel, or as a devil, visiting various children and motivating them to shape up.)
December 24: Christmas. (Celebrated only when you can see the golden pig and three stars in the sky!)
Not technically a public holiday but still of importance:
January 16: anniversary of student Jan Palach's death by self-immolation in 1969 in protest of the Soviet invasion; the twentieth anniversary of Palach's death sparked demonstrations against the Communists that resulted in the Velvet Revolution. Palach's grave in Olšanská cemetery always has flowers on it.
Finally...if the Czech team wins gold, silver, or bronze in the world ice hockey championships, the effect is more or less that of a major national holiday.
(This is not a complete list--anyone else should feel free to add dates.)