A chaos pad seems to be a
tool that is used mainly by
DJs, though the only song I heard/saw it in is
Everything In Its Right Place (when played
live) by the incredible
english band
Radiohead. More precisely it is used by Radiohead's
lead guitar player (and
multi-instrumentalist), the great
Jonny Greenwood.
It's probably called 'chaos pad' because, well, you can put some chaos into the music your playing and because it's a small, (not so) flat box with a display on it. The display seems to be some touchscreen type of thing, it (the chaos pad) can be controlled by moving your finger around the touchscreen/display/whatever. When Radiohead play eiirp live, Thom Yorke starts playing the piano riff, while Phil Selway is drumming a bit and Colin Greenwood plays his bass. Thom's singing and his organ stuff are recorded, and then Jonny uses the chaos pad to mess around with the voice.
By moving his finger into different corners of the screen, Jonny can play with Thom's voice (though you could play around with anything I suppose). I'm not really sure about everything you can do with the chaos pad, but controlling the speed and pitch is what Greenwood is doing most of the time I think.
The usage of this "instrument" makes the live version of Everything In Its Right Place a bit interesting, because it's different than the studio recording. I'm sure there are many more possible usages for the chaos pad, it seems to be a very interesting tool for people who want to sample stuff..
Anesthos, the unarmed