1. A computer system for targeted advertising in a computer network of users, the computer system comprising: an advertisement database storing at least one advertisement; and at least one computer server coupled through a global network to client computers associated with one or more users, the at least one computer server being configured to: determine a rank for each of the one or more users within the computer network of users as a function of user demand and user importance, and target the at least one advertisement for display to at least one of the one or more users based on the rank of the at least one of one or more users.