1. A method of delivering rented machine readable media to a subscriber comprising the steps of: providing a maximum number of machine readable media items (Nmax) which the subscriber can have out at any moment in time; delivering a machine readable media item to the subscriber in accordance with a priority specified by the subscriber to a computing system; incrementing a count of machine readable media items out (Nout) at the computing system; determining if Nout>=Nmax at the computing system; when Nout>=Nmax, setting a timer to a predetermined delay at the computing system; and delivering another machine readable media item to the subscriber after expiration of said predetermined delay, even if Nout>=Nmax; wherein a number of machine readable media items in excess of Nmax can be in the subscriber's possession and/or in transit to/from the subscriber.