So apparently since 5.2, more languages are supported by default in WoW. One of these being Japanese.
The game will now allow you to type characters from the Hiragana alphabet.
The fun part of this, is that all of the English characters you use in the same sentence will be using a different font.
Image example using: "十 Battlemaster Trinket used! 十" as opposed to regular "Battlemaster Trinket used"
Attachment 12933
You can even use the symbols that look like little people: 훗 옷
As for exploitative use, I've not tested how this translates between horde/alliance yet.
But I gets me noticed in trade chat while selling things. Though I admit, most of these are /w of "HOW U DO DAT?"