On a recent trip to the northeast I had the opportunity to visit the MIT Museum. One of my favorite exhibitions was of several of Arthur Ganson's works of moving art (link to videos below).
This artist makes REALLY CREATIVE machines of art using wire and surplus metal which are then set into motion by either an electric motor or a hand crank. At the museum, most exhibits had a button to press to set the machine into motion. They were really, really cool. I've purchased and passed around his DVD (videos of a few minutes of each of maybe 40 different machine creations in action) and everyone who has seen it so far has been entertained and intrigued (adults, young adults, and kids alike).
His web site has a few of his videos available for Internet viewing. To get an idea of what I'm talking about check out "Machine with Artichoke Petal" at his web site: http://www.arthurganson.com/pages/Sculptures.html.
If you like what you see, I do recommend his DVD for more.