1. A computer-executable method for multi-domain clustering, comprising: collecting domain data for at least two domains associated with users, wherein a domain is a source of data describing observable activities of a user; estimating a probability distribution for a domain associated with the user; estimating a probability distribution for a second domain associated with the user; and analyzing the domain data with a multi-domain probability model that includes variables for two or more domains to determine a probability distribution of each domain associated with the probability model and to assign users to clusters associated with user roles.