Serverside blacklist! This way, updates are easily possible, affect everybody automatically and the client can\'t be modded to allow what it usually doesn\'t. Of course, not a permanent connection, but only when you hit \"connect\", the server would say \"no, bad person, try again\". Furthermore, once a name has been classified as \"no good\", it could be added and the next time the appropriate person tries to connect the server would refuse to connect and the client would automatically prompt for a new name.
Surnames are good, and I said somewhere that I\'d like \"high-order nicknames\" like \"the dark\" which would not be selected by the player but given by others (but modded, of course, so RARE).
Conventional nicknames (like Seytra) wouldn\'t need to be unique, but would only show up after you told the person what it is (Hi, I\'m , but my friends call me \"Rew\"). This way, they wouldn\'t be universally known and therefore be pseudo-unique.