1. A computer-implemented communication method for message transmitting and message receiving users having related health characteristics, comprising: the message receiving user defining at a receiving user computer personal health message receiving criteria for determining messages to be received from other users who conform to the personal health message receiving criteria, the personal health message receiving criteria including personal or health characteristics relating to the message receiving user; the message transmitting user defining at a transmitting user computer a message and personal health message transmitting criteria for directing the message to other users whose personal health message receiving criteria conform to the personal health message transmitting criteria, the personal health message transmitting criteria including personal or health characteristics relating to the message transmitting user; and transmitting the message to any message receiving user with personal health message receiving criteria that conform to the personal health message transmitting criteria.