This paper describes ThumbTEC, a novel general purpose input device for the thumb or finger that is useful in a wide variety of applications from music to text entry. The device is made up of three switches in a row and one miniature joystick on top of the middle switch. The combination of joystick direction and switch(es) controls what note or alphanumeric character is selected by the finger. Several applications are detailed. Keywords One-Thumb Input Device, HCI, Isometric Joystick, Mobile Computing, Handheld Devices, Musical Instrument.