Modular personal networks (MPNs) are disclosed that include multiple devices that may be worn, carried, or used in close proximity to a user. The devices communicate wirelessly. Devices include security circuitry that prevents them from being used in a different MPN once the user has configured them. Devices not designed for use within an MPN can be included in the network using a bridge device. Devices can be integrated into items of jewelry, such as earrings, rings, pendants, and bracelets. One item of jewelry, such as a bracelet, can support multiple replaceable modules with variable functions. Functions of the MPN can include communications, entertainment, medical monitoring, sports monitoring, personal organization, and games. Multiple users each with his or her own MPN can use them to collaborate in creation of music. An MPN can be used for mobile recognition and logging of wildlife.