I would loooooove to have a random LFO added to the vibrato effect. I do a lot of downtempo stuff, and being able to slightly vary the pitch of my guitar randomly while playing would be an amazing addition. In fact, I feel a random or sample/hold type LFO would be a great (and fun) addition to some of the other effects that utilize a waveform (tremolo, etc.).
Also, a bitcrush/bit reduction effect would be pretty tight; I don’t know if that’s in the works, but I feel it would be a great toy as well!
A vinylizer type effect that adds warbling and a dusty, dark feel would also be welcomed!