This is a great idea! What I would personally like to see is a frequency shifter, which is readily available as a supercollider ugen. Preferably very small amounts of shifting should be possible, as this results in wonderful barber-pole phasing effects.
Another, more involved idea is macro control of multiple parameters with one MIDI CC. The Line6 M5 that I had made this wonderfully easy.
Expression pedal implementation
Start with the pedal in the toe position. Once you have your effect parameters settings as desired rock the expression pedal to its heel position. Now set your parameters to your desired settings. Now as you move your expression pedal from heel to toe you’ll see all of the adjusted parameters move between these settings. All parameters affected by an expression pedal will show a pixel notch at the top indicating a parameter’s setting for the toe position of the pedal. You’ll also see a notch at the bottom that indicates a parameter’s setting with the expression pedal in the heel position. NOTE: In any case, the bar graph will automatically never display in the areas above the right-most pixel or below the left-most pixel, since these are the extremes that the pedal’s parameter control are set to go to. If no expression pedal heel and toe values are set for a particular parameter, there will be no pixel cutout in the graphic. TIP: If you want to “clear out” your expression pedal settings: Disconnect your expression pedal momentarily, tweak any parameters that you want to “clear” the expression pedal control of, and reconnect your pedal to start fresh with setting up your expression pedal control settings for those parameters.