I got myself an EMG 89, that's a splitable active (i.e. battery powered type with a high output which distorts with the amp on a lower level and gives super-distortion) humbucker. The coil tap on mine is operated by pulling out or pushing in an ordinary looking tone knob. I use a little two way switch to turn the pickup on and off. If I set the pick up selector exclusively to that pick up the on off switch can completely kill the sound producing this cool stuttering effect. If the pick up selector is selected so that my EMG 89 and my middle pick up are selected the kill switch makes a nice kind of tone and volume fluctuation, harsh and loud on the one hand, warm and quiet on the other. This latter effect is more manageable I find, I particularly like it with out of phase unison bends that wail and burn.
Some of Rage Against the Machine's Tommy Morello's sounds come from using an on/off switch.