i'm sure many of you have thought of this before, but on the last album I recorded I came up with a cool way to make screams or guitar rings outs or final drum hits etc to fade away (rather than simply automating the delay/verb send higher at the end) Basically whatever it is you want to 'disappear', copy that section onto a track so you have two identical parts running parallel to one another. On the duplicated track, stick on a pretty hefty LP filter at the end of the chain; say somewhere between 800hz-1.5khz... depends how extreme you want to go. You could also stick a touch of large verb on this track as well. Now as the scream starts, you automate the volume on the main track to go from full volum to silence. Then do the reverse on the LP/verb duplicated track, automating from silence to what ever final volume you want. And there you have it. Rather than simply sticking on more verb or delay at the end of a scream, this will make it disappear in a slightly more 3D way.