Not completely instrumental, but A Man A Plan A Canal Panama by the Fall of Troy. Also The Gallery by Muse. EDIT: Not trying to brag, but I've seen him play it live, and it is quite a piece of music. :) He really is excellent live if you ever get the chance to see him. I had just written an instrumental last week, and titled it Ocean, so I listened to this one out of curiosity. It EASILY trumps my two other suggestions. This song is EPIC, and I do not use that word loosely.