Norwegian jeweler Miriel Design (AKA Josephine Ryan) has created a bunch of kinetic solar system necklaces, available in her Etsy store. Here's a set of photos of them, and here's her discussion on Reddit. The pieces vary in price, from $380-$500, depending on their complexity, but they're all flat-out gorgeous, and represent a tremendous amount of precision labor.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.