1. One or more computer-readable storage devices comprising computer-executable instructions for administering file sharing over a network, the instructions comprising instructions for: receiving, at an extensible plug-in architecture and from a client, a request for a file stored on a host, the request being received at an extensible plug-in interface interposed in a communication path between the client and the host; exposing the request to a request administration module; relaying the request for the file to an intended destination of the request; receiving from the host a response to the request for the file; exposing the response to a response administration module, the request administration module and the response administration module comprising plug-in modules within the extensible plug-in architecture, the plug-in modules being configured to intercept the request, manipulate the response and track a plurality of file sharing transactions; filtering the response from the host according to instructions from the response administration module, prior to relaying the response to an intended destination of the response, filtering the response comprising appending a digital rights management element to the response or to data associated with the response, the digital rights management element comprising a digital signature or a watermark; and relaying the response to an intended destination of the response.