Often I'll download things from file sharing networks and find errors in them. A music file will have erroneous metadata, for instance, or a document will have OCR errors. I'd love to fix the errors and re-upload to the benefit of everyone else who has a copy, but that wouldn't work because file sharing is always based on a hash of the file, not on a file name or other identifier, and the erroneous version of the file is the only one people will see, since it is already ubiquitous.
Has anyone ever done any kind of work on a file sharing network that lets you identify revisions of a file, so the documents behave more like a wiki that people can edit, and still retain the identity of the previous version? People who already have a copy could just download the "patches" and decide if they want to keep them in their own copies or not.