Broken and The Downward Spiral are IMO the hardest (or darkest) albums by NIN, but 'The Hand that Feeds' is my favourite song by NIN.
Static X and System of a Down
What else - Gawd, where do I start? Type O Negative, My Dying Bride, Alice in Chains, Ministry, Epica Fear Factory, Slayer, Metallica, Marilyn Manson, The Mark of Cain, Rob Zombie, Rammstein, The Offspring, The Clash, AC/DC, Staind and the list goes on but you can't beat TISM!
