1 octave midi bass pedal, ala "Low-Lab".
Just a simple, stripped down version of a Keylab controller, in a one octave midi bass pedal form akin to a Roland PK-5 or PK-6, with ability to foot select scenes or sounds, and scroll through presets in a live set. Add bus powering through a USB connection, and you're good to go.
I'm holding out on this dream, rather than defaulting back to using the Roland units like I've used in the past.
From there could hook up my laptop, or iPad, and have a bevy of all of my recorded sounds ready to trigger with my feet.