Then there's the expanded talent contest. Can you sing, dance, or make people laugh? Send 'em a YouTube link with your intended performance and make sure you keep it within their suggested limits so they can use it during the con if they like it and you.
There's also an art and a movie contest, for the artistic and visionary types among us. So go ahead and check out the dungeon journal for the BlizzCon contests. There's also an email address for any questions you may have - BlizzConContest@Blizzard.com.