Justsomething 'miscellanious' concerning names which I find a lot of players don't know (or don't think of):
Your Friendslist is your friend.To my knowledgeyou can see if a certain name exists on Unity by trying to add it to your friendslist. If it exists, it will be added (also whenthat player is off-line!). If it does not exist it will not be added (alsomeaning: will be free to use as a new name for you...).
Great way to see ahead if a new name you have in mind already exists or not.
Also a nice help if youwould not mindgiving away the name of one of your ownrarely onlinealts: by typing the name with the other _shard(s) behind it you can find out within two tries at mostif a counterpart nameholder exists, and if so in which communityyour 'counterpart nameholder'must be; after that you can contact him/her directly from the friendslist, or when this player is not online you will know which player-channels to go to (old-shard-specific channels have been made again on unity), which groups of players to askif they knowthat counterpart, etc.
The other way around can be near to impossible; so why not take a few minutes to see if yóu can help anóther instead... make someones day maybe[:D]