I am going to be hated for saying this.
I find Slipknot a more agressive version of Mudvayne. I find Mudvayne a more agressive version of Godsmack, I find Kittie just plain cool. These bands, to me sound similar to The Crown, Bloodbath, even Carpathian Forest. No they don't sound alike but there are a lot of similarities.
I do only have one cd by Slipknot I have Iowa, the one I have from Mudvayne is LD50 and I have Spit by Kittie, I also have a Stink Bug cd which more or less fits in there, and I have 2 Godsmack cd's. I think my age is what stops me from liking these artists better. The hatred and angst that they spew is not something I identifiy with. I do like Godsmack and I don't know why I like Kittie but I do. In my book you could call them all nu metal. Which is a more fitting description than calling Motley Crue metal of any kind.
I have not heard Disturbed, but I should. Maybe someday.