Anonymous(!) on the EU Forums has suggested Blizzard take a note out of LOTRO's book and implement an /anonymous flag, which enables players to "vanish" from /who. I assume it would also work on Friends and Guild lists, kind of like hiding your online status on MSN or ICQ.
I happen to think this is a cracking idea. Being able to play without detection certainly appeals to me. Sometimes you just want to be left alone. I speak as a Warrior and a Holy Paladin, every few minutes I get whispers asking me to tank or heal somewhere, it's infuriating sometimes. This solution would be excellent.
The original poster also had other reasons this might be handy, namely from a PvP point of view. This function would hide your character name and stop other players from being able to inspect you, possibly future Arena opponents.
What do you think, good idea or bad?