1. A computer implemented method of locating expertise, comprising: in a processor: associating experts with respective certain objects, each object inheriting from classes in a mutable ontology-based hierarchy, said associating resulting in respective correspondences between experts and the certain objects, wherein the mutable ontology-based hierarchy is extendable on demand such that said associating includes adding objects or classes, on demand, to the ontology-based hierarchy; using the correspondences in a computer processor routine executed by the processor and finding a candidate expert about a particular subject area, the candidate expert being in one of the correspondences associating the candidate expert with one of the certain objects, said finding being ontology-based and allowing the certain object associated with the candidate expert to be found from the particular subject area whether the particular subject area is a relatively specific topic or a more general area of expertise than the certain object; and displaying as output an indication of the candidate expert.