What about a mod that changes the visible name

[Otter]

A lot of players push the line on family friendly servers. My thought is that if there was a mod that allowed for a visible name substitution in chat and on the visual display over a players head, it might be an interesting tool to filter the players who push the edge of appropriate behavior.

[sorcerykid]

Why not just block them from joining in the first place, or ban them if they have already joined? That seems like it would be far less complicated a solution, because masking out the name everywhere in-game would be extremely complex.