The Mandelbulb is an attempt to extrude the classic Mandelbrot Set fractal into three dimensions. I'm not enough of a mathematician to say whether it accomplishes this feat, but it is utterly arresting.
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.