We'll have more costumes today and tomorrow, but this one was too good to not share right now. YouTube user onemeeeliondollars has posted video of a costume he apparently made with two iPad 2s that makes it look like you can see clean through his torso. As he says in the video below, you just cut two holes in a shirt (that's how you make every great Halloween costume -- just ask Charlie Brown), put a little fake blood around them, and then strap two iPad 2s to yourself (they have to be iPad 2s, of course, for the camera).
Then, he set both iPad 2s to run a FaceTime call between them, and voila -- one iPad 2 outputs the video of the other, and vice versa, and you get (kind of) an optical illusion where you can see right through a person.
Ok yes, it's a little hokey, it doesn't quite work perfectly, and you might be risking your iPad 2s (not to mention that your networking setup has to be tuned for your trick or treat route or the party you're attending; for his costume, he says he's using mobile WiFi). As he also points out in the video, if the costume itself isn't fascinating enough, they double as, you know, actual iPad 2s.