I'm a fan of Apocalyptica. The band adapts metal songs in an orchestral manner (three members are classically trained cellists). I saw them live once at Rock on the Range and when I'm in the mood for something just a little different, I tend to pop them on my stereo.
It's pretty interesting the band is releasing Wagner Reloaded - Live in Leipzig next month. 2013 is the 200th anniversary of Wagner.
To that end, Apocalyptica just released the video for "Ludwig Wonderland." Watch. I'll definitely be getting this album!