You're right, that could work in theory. In practice it would be difficult to manage and keep track of all the links, update them if the file is moved, etc. I suppose hard links would avoid that, so that might be a reasonable way to implement tags, I agree. My main goal would be to manage this via a tag-like UI, so that I don't have to do this manually. And at that point I might as well just store the metadata in a proper DB instead of the filesystem...