If you want the real crunchy riffs, you just need to pack a CD out with as much industrial type metal as possible. A few recommendations:
Soulfly - Prophecy (the riff in that song causes minor earthquakes when played loud)
Static X - Push It / Bled For Days / This Is Not / Otsegelectric (insanely fast riffs)
Coal Chamber - Row Boat (slow, but real heavy and dark as f*uck to boot)
Mudvayne - Dig (needs no introduction)
Spineshank - Synthetic (like Static X, but with a more punky vibe)
Rob Zombie - Dragula (stupidly loud)
Adema - Needles (don't ignore this just because it's Adema, it's actually very heavy. Vicious bassline.)
Killswitch Engage - Numbered Days / My Last Serenade (duh)
System Of A Down - Deer Dance (very heavy core riff)
36 Crazyfists - Slit Wrist Theory (mellow at first, but the chorus is huge)
Pantera - Mouth For War / Live In A Hole (brutal)
and as tabby said, pretty much anything by Rammstein & Fear Factory would fit the bill nicely.
Also check out Hatebreed, Devildriver, Drowning Pool and of course, the mighty Slayer 👆