Did you know Belgium:
Allegedly hosts the third largest festival in all of Europe. The Gentse Feesten is a 10-day music festival in Ghent during July, dating back to the 1800s. The last day of the fest is called "the day of the empty wallets."
Is responsible for the saxophone. Wallonia native Adolphe Sax played the flute and clarinet and designed instruments for a living, with his most notable work being the invention of the saxophone. He took after his father who also designed instruments, working the most with horns.
Django Reinhardt grew up a gypsy, taught himself pretty much everything he knew, and created a new jazz guitar style (despite his missing fingers).
Likes European country music. A lot. Antwerp's Bobbejaan Schoepen, a vaudeville/folk/country/ musician/entrepreneur/comedian/professional whistler, became one of the richest people in the nation thanks to his musical innovations and talents. He even opened his own Bobbejaanland amusement park in the '60s.
Gets down on a lot of mashups and Afro-pop music. Contemporary music in Belgium includes Congolese-Belgian artists as well as DJs that were crucial to the growth and popularity of mashups (like Soulwax and their 2 Many DJs project).
Bonus -- out of all of Belgium's music, apparently this is the one that became a worldwide hit.