A computer input device (e.g. a mouse) with a finger-triggered sensor is described. The sensor generates input signals in addition to the conventional mouse signals generated by click buttons, tracking device and scrolling wheel. The sensor may be an optical sensor, a touch-sensitive sensor or other types of sensors. The signals generated by the sensor, either alone or in combination with other signals generated by the buttons, tracking device or scrolling wheel, may be interpreted to generate various messages for the operating system and/or application programs. The interpretation may be performed by a circuit on the input device, by a driver program on the host computer, or both. The sensor may be provided on a mouse, a laptop keyboard that has a pointing device, an external keyboard equipped with a pointing device, or on a stand-alone device that can be electrically connected to a computer through its available ports.