WEEK FOUR BONUS - ANSWER

Thanks to most of you who got your bonus answers in! The answer:

Abba got their big break in 1974 in the Eurovision Song Contest singing "Waterloo".

I love Eurovision. It's like American Idol on crack. I have the soundtrack from the 2001 competition, including my favorite Turkish boy band singing "2 Much". And if you haven't heard Stephan Raeuber's "Wadde Hadde Dudde Da", you haven't lived.