I have recently come across a singing group known as Gregorian, a collection of singers who take pop and rock songs and turn them into Gregorian Chant. It sounds like a completely insane concept, but it works really well–amazingly well, actually. Just listen to their rendition of “Into the West” from The Lord of the Rings:
It appears they have released some traditional chant albums as well–mostly for Christmas–but they’re better known for their contemporary chant arrangements. And I must say I think Gregorian is one of the most talented groups I’ve ever heard…certainly better than a lot of mainstream acts.