I remember seeing a video of Les Paul playing in the early 60's i think, and he has this amazing guitar with lots of switches and knobs.
And he hits one of the knobs and start playing a rythm, and then he switches the knob of and stop playing, and then turn up a knob and the rythm part he just played comes on!
And then he hits another switch and puts a melody line on it and do the same thing, so he has a rythm and a melody.. so now he starts to improvise over that, and while he is improvising he starts to tweak around with other switches and knobs on there, giving him reverb and chorus effects etc.. amazing that he did that in the 60's.
(I tried to find it on youtube with no success.)