you asked for a pedal, but what should it do?
I guess you know what s&h is (if not
http://en.wikipedia.org/wiki/Sample_and_hold ) so you should specify what you want to be controlled by s&h
of course the moog control processor cp-251 has s&h functionality, but you need another pedal to be controlled by it - say the frequency of the ringmod, the speed of the phaser...
btw, zdravo fuNKmaster!