Jiikae
Typing of the Red
What if you and a friend, at home, were playing together and one of your online friends came in/interrupted the game. You could turn this option on or off by going to the rules and turning WiiConnect24 on or off. Your friend would connect to nintendo wifi, and see that you have a game going on and just join. No special movie though.... his character generates on the platform and gets to fighting. Kind of like arcade fighting games like tekken, but quicker and online. Since the Wii is always online I don't think this feature would be difficult to put in, although problems like lag when your friend generates could happen but I'd be willing to overlook that.