1. A method of associating user records across a plurality of cloud-hosted services, wherein (i) each of the user records comprises a plurality of fields relevant to an identity of an actor and values for at least some of the fields and (ii) at least some of the user records lack sufficient data to identify a unique actor, the method comprising the steps of: receiving a request from a first user to register at a first cloud-hosted service site; creating a first user record for the first user; identifying a second user record associated with a second cloud-hosted service based on similarity between at least one field value in the second user record relevant to the identity of the actor and a corresponding field value in the first user record relevant to the identity of the actor; computationally determining a probability that the first and second user records are associated with a first actor based on similarities between additional corresponding field values in the first and second user records; and if the probability exceeds a threshold, taking an action with respect to the first user record on the first cloud-hosted service based on a score associated with the second user record.