1. A method for transmission of digital medical data between at least two geographically separate locations connected by data paths of limited bandwidth, the method comprising the steps of: separating said medical data arriving at one of said locations into at least bulk content and metadata; associating said bulk content with a content identifier; selecting said locations to which said bulk content is to be transmitted based on a calculation utilizing at least one factor selected from the group consisting of the desired degree of content duplication, storage capacity available at each of said locations, geographic distance to each of said locations, transmission cost to each of said locations, data path bandwidth to each location, current utilization of the data paths to each of said locations, processor utilization at each of said locations, and the likelihood of retrieval at each of said locations, said likelihood of retrieval being calculated using at least one of information contained in said metadata, from requests to use said bulk content, prior usage of said bulk content, from information obtained from a system that manages patients' appointments, and from information obtained from a system that manages uses of said bulk content; selecting optimal ones of said locations by calculating the relative ranking of at least two of said locations using at least one of said factor and said likelihood of retrieval, wherein which of said locations are optimal can change over time; updating which of said locations are selected as optimal; transmitting said bulk content to the selected said optimal locations for storage; extending said metadata to comprise said content identifier and a list of all of said locations where said bulk content has been and stored; and transmitting said extended metadata to at least one of said locations and storing it; wherein said relative ranking is determined by calculating a score for each of said locations based on a weighted sum wherein weights are selected and multiplied by values obtained from at least one of said factor and said likelihood of retrieval.