Nightwish frontwoman Anette Olzon contributed guest vocals to the song "Cathedral Walls" by fellow Finns Swallow the Sun; you can watch the video below. (Anette's not in the clip; she was doubtless too busy working on Nightwish's new album Imaginaerum and its accompanying movie.)

Nightwish's Imaginaerum will be in stores on Tuesday, January 10, but you can pre-order a very special deluxe package right now that includes instrumental versions of every track on the album, four exclusive digital-only bonus tracks, instantaneous digital delivery of the album, an exclusive T-shirt, and the chance to win tickets to see the band perform in Los Angeles on January 21 - all for just $33.99! Click here to order!