Can't believe someone said Amy Lee from Evanescence. She's doesn't even have control over thirds or fifths. My choir teacher in high school video taped her when she was on tv sucking at what she does best.
Anyway, no Sebastian Bach from Skid Row? For something more updated try An Absence of Empathy, the second Frameshift record.
James LaBrie from Dream Theater is good, no one likes his voice, it's kind of an acquired taste like Geddy Lee, but he's excellent, Arjen Lucassen said he was pretty much a solid one-take vocal track. As far as Dream Theater vocalists go, I am definitely a bigger fan of Charlie Dominici.
Devin Townsend is good when he's not screaming, Terria was pretty impressive.
Anyways, I agree with whoever said Mike Patton, David Lee Roth, Steve Perry, and Corey Taylor. Corey is just in the wrong music, he could be doing so much better stuff than slipknot.