Some kind of engine which searches for things. You could use it as a power source by placing the thing that it is to find onto its back.
Obviously, it would have all sorts of useful 'find things' applications too. I'm envisaging it as sort of crab-like with lots of eyes on stalks. About knee high.
Of course, Google would have you use pigeons. But who would power their evil air-ship with mechanical pigeons?