I'd like to include Meshuggah in this. They pretty much only have like 5 notes a song. Pretty gay...
from what i've read, this isn't a record, but a friend of mine from a Christian Screamo band did a 22.3 sec scream yesterday.
Longest fake scream Iv'e heard is the begining of the original Stromblast song.
Longest real one is in Emperial Live Ceremony on An Elegy of Icarus. At the end of the song right before they go back into the melodic vocal part Ihsahn screams "Icarus" for what I'm pretty sure is about 3 years.
Well, Maynard James Keenan has a live recording of a little over 20 seconds during "You Lied" on the Salival CD.
And aside from that, I would be willing to bet there are thousands of Tool fans that have seen them in concert and witnessed his tremendous vocalization power.
The few I've heard:
-Micke Å does some pretty long ones in like Black Rose Immortal and Brave and Crimson
-That 20-second long in the beginning of Silence Calls the Storm by Quo Vadis, I think it's a bit fake though
-20-something in The Grudge by Tool
And then I'm probably forgetting something really obvious. But what else is there? I've heard about Peter Tägtren doing a 40-second scream, on what song is it or was it just live or something?