A trackball is basically an upturned mouse. Rather than rolling the mouse on the table top it is a static device, with the ball on the top being moved using fingers, thumbs and palms. Larger trackballs are often suitable for use by feet.

Using a trackball	Demo of Kensington Expert Pro Trackball
Logitech Trackman	Logitect Trackman v Logitech Marble
RoleePolee Handheld trackball	Demo Of Sam-Trackball (RJ Cooper)
Kensington SlimBlade Trackball	Kensington SlimBlade (Media Mode)

Trackball World . . .