The McCallum was horrible.
The one that's haunted me forever was Clint Malarchuk, goalie for the Sabres way back. Just thinking about it freaks me out.
Here's the youtube.
But seriously, don't watch.
I should note, he had 300 stitches, and was back practicing again 4 days later, so it wasn't that catastrophic an injury, but just looked horrific.