I personally want a mouse with a pinpoint 8-directional joystick in it, and a custom driver to map said stick's movements to the numpad (ie, forward-back-left-right are 8-2-4-6 respectively, rolling the stick two units clockwise is 9, anticlockwise is 7, forward to back is -, back to forward is +, and obviously clicking it down is enter. It sounds awkward but I've played fighting games all my life so it'd be awesome for me (as odd as it sounds).
That or just somehow bind my mousewheel+left mouse buttons to be like that, since this mouse has a mousewheel with tilting.
