I'm working with a group and the University of Minnesota that's trying to figure out a way to listen for respiratory ailments in chickens. We need to compile a library of health (and sick if you have them) bird sounds. If you have any audio or video of your birds vocalizing, please upload it here: http://j.mp/ChickenSoundsUpload
I'm literally making a post to bring this a little more attention. I can see this being very useful. Especially for newer owners. It sounds like something that might help people start treating sick birds before they keel over, or maybe just isolate the sick birds before they make the rest of the flock keel over.