Champions Online players! Cryptic has worked out an interesting system that's poised to alleviate the classic issue. You can read about it in the latest Ask Cryptic and also go over a ton of other crunchy information on the game, too.
It works like this: Now everyone can be named Fellbat, but you can only have one character per account with said name. To prevent confusion when looking for a person in-game, you specify the player via their handle. So for example, "Fellbat@Massively" or "Fellbat@Boboid" would reach two different players.
Though a perfect solution it may not be, we think it's far better than having to come up with a second, third, fourth or sometimes even fifth name in lieu of the one you really wanted.