Korn definitely should be on the list. They truly created a whole new genre (a very popular one) within metal and hard rock. As much as people hate them they did something very original in the early 90s. Especially during a time when metal had one foot in the grave it seemed. But now I kind of wish they had never come around... as much as they influenced a whole wave of bands... most of those bands were utter crap.
At The Gates... another good one!!