Modder Jani ‘Japala’ Pönkkö added an LCD display (Nokia 6610) into a Logitech G5 laser mouse. Full instructions here.
The controller requires adding three more wires to the mouse. These are connected to a parallel port. The screen can only show about 1 frame per second, but that is fast enough for general statistics or showing photos. It’s a really clean build. A clever trick was using a piece of plastic from the blister pack to cover the screen since it was already the same shape as the mouse