I would like to create a node with unique rankings of other nodes. In other words, I would like the user to give one document a First place, another document second place etc. I want these to be unique so there's only one first place, one second place etc.

Has anyone implemented this? It would be okay for me to do this in the browser layer with Javascript even though someone might spoof the system. Ideally, the server would also check for correctness.

Thanks.