Today is the 40th anniversary of the mouse. Since then, it's evolved into different shapes, sprouted buttons, lost its tail and mutated all kinds of other crazy ways. But everyone has a favorite.
My favorite mouse ever is Logitech's MX500, which set their ergonomic standard for years, all the way through the wireless G7 gaming mouse, and to some extent, their current Revolution series. It doesn't have a laundry list of features or 10 million buttons—it's just a simple, but perfectly evolved mouse. The worst mouse ever has to be Apple's hockey puck, no need to explain there. Tell us who made your favorite in the poll, and get more specific about it in the comments.