The Old Gods of Asgard songs in the game are performed by Poets of the Fall. A band I hadn't heard of before but I'm glad I looked into them. In particular I want to share their video for Carnival of Rust. You can check it out below.
I was sent the link for this last night, but thanks to being busy with the Ten Revolutions celebration on The Dividing Line I didn't watch it until this morning. This is a good thing because I can't imagine what my dreams would have been like if I had watched it before going to bed.
This joins together a few of my favorite things. Music, soundtracks, John Williams compositions, a capella, geeky videos, multi-track recordings of a single performer, Star Wars, Indiana Jones, Close Encounters of the 3rd Kind... Oh, just watch it already! ;)