I like big trackballs, probably because I am used to a trackball since having used my first PowerBook 180. And I love Trackpads, as you can use those things silently. Both trackballs and trackpads require much less space on a desktop than a mouse in use. ALPS provided external ADB trackpads for the Macintosh, with two buttons and configurable to support tapping, dragging etc. An external trackpad is a perfect mouse replacement for presentations or similar circumstances. It works perfectly even wearing examination gloves.

(Sorry, but no multi finger taps or gestures up till now.)