[quote name='ChibiJosh']There's also Godspeed! You Black Emperor, 65daysofstatic, and Mogwai.[/quote]I don't mean to be a prick, but I think it's actually "Godspeed You! Black Emperor". Check your copy of "Yanqui U.X.O." -- a couple friends and I actually had an unreasonably long discussion one time about where the exclamation point goes, and I used my copy of "Yanqui" to settle that.
But anyway, he's right. I haven't heard of 65daysofstatic, but Godspeed and Mogwai both have my vote.
Also, I know they're not instrumental, but for those of us who don't speak Icelandic, they might as well be: Sigur Rós. Their new record comes out today, and it's only $7.99 on Amazon!
Oh, I just thought of another one: Dirty Three. They're instrumental, right? Yes, I do think so.
And Rodrigo Y Gabriela. Not what typically passes as "indie", but awesome nonetheless.
(By the way, Explosions in the Sky does count.)