If you love Japanese ice-spheres in your booze, but don't want to spring for a pricey bespoke machine to accomplish the trick, you can always pick up one of Muji's silicone ice-ball molds, a steal at £7.50.
Silicone Ice Ball [muji.eu]
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.