I think Sick Sick Sick by Queens of the Stone Age is pretty intense.
Some other possible candidates would be Black Dog or Achilles Last Stand by Led Zeppelin. Black Dog can sound kinda wimpy when you start out, but by about 1 minute to the end, you just can't stop head-banging. And Achilles Last Stand is proof, I think, that a song doesn't have to be loud or incoherent to be intense. It's a ten-minute long marathon, and you start wondering how anybody could possibly have enough energy to rock so hard for so long.