R&P: What are some vocally challenging songs?

anything by the fantabulous Diamanda Galas... this slinky tune with John Paul Jones showcases her range and sounds ha ha! 'Skotoseme'- a href="http://www.youtube.com/watch?v=f0AIjnQ8t30" rel="nofollow"http://www.youtube.com/watch?v=f0AIjnQ8t…/a ... i love this woman ;)