We have disclosed a modular personal network (MPN) that includes multiple devices that may be worn, carried, or used in close proximity to a user. The devices communicate wirelessly. Functions of the MPN may be modified by adding or removing components. The MPN may communicate with a personal computer. General purpose devices may include a control unit, a display, a user input, and an audio output. The MPN may provide a variety of functions, including time, communication, entertainment, organization, guidance, athletic, medical, travel, outdoors, identity, security, and military.