Plus, registering for the Blizzard store comes with another perk. You can register for the Beta Test lottery, which is a chance at being chosen for upcoming beta phases of various games. Wrath? Starcraft II perhaps? All of the above? Who knows! I've been considering getting into the WoW TCG, so if I get a shot at a beta test out of it, too... hey, why not?
Edit: The Blizzard EU store is not yet live, but I imagine it will be soon. Sorry, Europe!