Neil Young's Whizzer.

The craziest pedal... I kinda don't believe that it works, but Neil Young had his tech build a pedal that physically turns knobs on his amplifier. It can store presets for meticulously precise settings. It's called the whizzer, one part sits on top of the amp(pictured below) and the other part is a huge red stompbox(above).

thats it on top his amp, next to the headstock of the guitar. and a glass of milk?

more about the Whizzer (taken from Wheat Thrasher Neil Young Archive) :

"On top of the amp is a Whizzer, a device that physically turns the amp's knobs. Neil came up with the idea, and Sal Trentino, his amp tech, made the first one. This was a 2 position Whizzer that he used starting on Rust never Sleeps in 1978. The new one was made by Rick Davis in 1991. Its got four presets that completely control the three knobs on the top of the amp. He locks in the preset he wants, and it will always go back to that particular spot. We find that when you have the volume and tone all the way up, by turning that second volume knob up to about 10, it starts to fade away.But right before it starts to fade away, something else happens, and that has to be in exactly the right position. You can't breathe on it, or it fucks it all up.
Here are Neil's Whizzer settings: For the highest volume, we have both the tone and the main volume on 12 and the second volume knob is at about 9.9. When it really compressed and breathing and screaming, that's whats going on. You can hear it on "Cortez". If we push it past 9.9 the sound goes away. The next button down moves his volume to 10, which just cleans it up. It's still broken up but its less garbled. The third button sets his volume on 6 with his that other volume still at 9.9 and the tone just down a little. The fourth preset moves one volume to 3,the other volume to 0, and backs the tone off a bit, its really bright and clean, almost country sounding. "

http://www.demonoid.com/files/details/1734014/18923076/