Korn? Korn?! Man, I haven't listened to them since I started playing guitar, and realised how inanely boring and unchallenging the music was (as well as it totally being targeted towards a mainstream audience. Metal for young kids. AKA Nu-metal).
If we're talking metal... here are some REAL metal bands/acts:
Anthrax, Dream Theater, Iron Maiden, Jason Becker, Yngwie Malmsteen, Megadeth, Metallica, Pantera, Testament, Exodus, DragonForce, Tony MacAlpine, Shadows Fall, Hammerfall, Manowar, Stratovarius, Symphony X, Cacophony, Helloween, Rusty Cooley, Symphony X, Vinnie Moore and a few others I've forgotten.
Check 'em out.