Option for "arm-swinger" locomotion
A method of locomotion that uses the velocity of the player's hands (When a locomotion button is pressed) and translates it into forward (Or sideways) motion.
Obviously this would require a separate set of key-bindings but with all four locomotion directions handled by physical movement that opens up four more directions (+four click directions) for additional inputs anyway.
It's also a little bit of exercise. =P