Although I'm not crazy about A Perfect Circle, or Tool...
I've seen a Perfect Circle in concert, and Maynard did something that was more warped than anything I'd ever seen or experienced before. The whole outdoor show was moshing, and moving around, and he just hit this one note that shell shocked everyone. It wasn't anything wild like Rob Halford could do, but it was a flawless, heavy hitting tone, that made everyone stop in their tracks. Dead. Zombies! It was messed.
Personal favorites: Curtis Mayfield, Halford, Chino Moreno (Deftones).