I just saw in a crap film this guy who had some thingey with wich he could detect spiritual activity, you know the kind. "Oh there is a high level over here now.."
Now, since I started building robots, whenever I see gadgets like that, I know how to make them. Only I do not know what sensor to use.
OK, it's a joke, but then again, what sensor would one use? Seriously? I would like to try to build one!