Fun! I'd love the option to increase (double?) range. It would sacrifice precision somewhat, so a toggle would be ideal.
A toggle for quickly visualizing notes would also be useful, as well as keyboard shortcuts — perhaps while one clicks the mouse on a given note, pressing the keyboard shortcut for another specific note gradually moves pitch in that direction, with programmable speed.
Oh, and clicking multiple times at the leftmost portion of the instrument (around 1/4th from the top) sounds exactly like Laurie Anderson's classic "O Superman" :)
A toggle for quickly visualizing notes would also be useful, as well as keyboard shortcuts — perhaps while one clicks the mouse on a given note, pressing the keyboard shortcut for another specific note gradually moves pitch in that direction, with programmable speed.