Instrumental BANDS

Liquid tension experiment
Spastic Ink
Also you might like Isis.(albums: oceanic and panopticon although they do have some vocals)
 
Borknagar recently came out with an all instrumental album, that I'm not too crazy about... I guess you already know about Burzum.. Empyrium is considerably instrumental.. oh Negura Bunget is instrumental.. but not much metal is completely instrumental because then I suppose it would be classical, no?