15. A service system for use in finding locally-relevant information in a physical or electronic document already possessed by a user, the service system comprising: a communication subsystem for communicating with a mobile entity of the user via a communications infrastructure that includes a mobile radio network with which the mobile entity can communicate; a query handler for receiving a query message from the mobile entity via the communications infrastructure, the query message identifying the document to the system; a location-determination arrangement for providing location data regarding the location of the mobile entity; and a document-reference determination subsystem for providing a reference indicative of where, in the identified document, information can be found that is relevant to the locality of the mobile entity as indicated by said location data; the query handler being operative to return to the mobile entity, via the communications infrastructure, the document reference provided by the document-reference determination subsystem.
18. A service system according to claim 15 , wherein the service system is adapted to handle query messages relating to documents from more than one publisher by accessing further service systems maintained by individual publishers.