The Kingdom of the Netherlands is, like the UK, a constitutional monarchy. Like in the UK, though with a great deal less pageantry, Her Majesty Queen Beatrix of The Netherlands opens parliament each year. (In fact, the British monarch is the only European monarch who is actually crowned. Other European monarchies have an investiture where they are in effect sworn in like Presidents.) This sort video in Dutch shows what happens at this affair. You can see the golden coach which Her Majesty rides in, the eighteenth century costumes accompanying it, and of course the hats worn by HM The Queen and HRH Princess Maxima, the latter being the spouse of the crown prince, Prince Willem-Alexander of Orange. It all ends with shouts of “Long live the Queen!”
An interesting trivia fact for you. The Netherlands has not had a king since the 1880s. During the entire 20th century, it has been ruled by queens. Queen Wilhelmina became Queen in 1880, though she was very young then. Her mother, Queen Emma served as regent until she was of age. Queen Wilhelmina abdicated in 1948 in favour of her daughter Juliana. Queen Juliana, who died in 2004, abdicated in 1980 in favour of her daughter the current Queen Beatrix who was born in 1938. One wonders whether Queen Beatrix will, like her predecessors retire in favour of her son. So far, though, she seems to enjoy good health.