White Cliffs of Dover by Mulletboy?

How about if its not an instrumental, but might as well be? Sigur Ros uses their own made up language (Hopelandic, a variation of Icelandic and lots of drugs) in order to create another instrument in the form of his voice. The singer from the Cocteau Twins generally did the same thing.

So getting that out of the way, I'd have to say:

Sigur Ros - Staralfur : Off of the Agaetis byrjun cd. Really, this is like crack for the ears. The guitar alone is enough to die for.

Tortoise - TNT: I have a live version (I think it's from the All Tomorrow's Parties) of this song that will just blow you away.

Godspeed You Black Emperor! - East Hastings : more post-rock goodness. The time changes, build-up of the melody and intensity...gives me shivers just to think about it.

But that's all post-rock type stuff. There's also stuff like Amon Tobin, DJ Cam's Mad Blunted Jazz entire double-disc album, Miles Davis's Bitches Brew (Or anything from the In a Silent Way sessions, really)...I could go on and on in the jazz world, so I won't.

Funny, the one category where I couldn't really think of any is rock. Oh well.

That's what I was gonna say - great instrumentals makes me think of Cocteau Twins, but it's not instrumental.

Failing that I'm nominating "Kinetic Ritual" by Klark Kent, aka Stewart Copeland circa 1979, because Mags already took the Pink Floyd stuff.

I think it's actually a bowl-cut gone bad.

Mountain Jam - Allman Bros., Eat a Peach. 33 1/2 minutes of greatness.

Apocalyptica - four dudes w/ cellos do Metallica. Odd, but really, really good.

Sandstorm - Darude, in the opening of Blade, there's a rave with vampires (how many convenient cliches, neh?). This is the song that's playing.

In Sounds from Way Out - Beastie Boys. Wha??? An entire album of B-Boys doing instrumentals? How bizarre. How delicious.