Nintendo has shown the "Zapper" attachment at some of the trade shows in which the Wii Remote is placed inside the Gun shell. I'm sure we'll see more "shells" at different points, depending on which companies want to make use of them. There was a picture of a plastic Link's Sword attachment shell on Play-Asia's web site a few months ago, but I haven't seen or read anymore about it lately. I'll do some more looking around and post anything I can find on it.