Freenet back links

Freenet, or something like it, could implement back links. Because documents cannot be deleted, a reverse link, if accurate once, is accurate forever. This would increase the linkiness of the network and the discoverability of documents which I think is a current problem. The mechanism could be whenever a hypertext document is inserted, and/or whenever a link from one is followed, metadata is also inserted keyed on the target of all the links. Whenever a document is accessed, the client or spider may also try to retrieve all the metadata about that document.

There is plenty of opportunity for spam sadly.