A few that comes to mind:
*Oceansize - An Old Friend of the Christy's - Heavy, Doom-ish, this is an epic tune.
*The Smashing Pumpkins - Mellon Collie and the Infinite Sadness - While it is just the album-theme and the intro music, it's just pretty darn perfect. I love it, and it sets the mood for the whole album.
*Pain of Salvation - Dryad of the Woods - Just a beautiful instrumental.