Wired's Adam Mann and Nurie Mohamed have a good roundup of a dozen-plus ferrofluid videos, showing off the remarkable aesthetics created at the intersection of magnets, liquid, and metal filings. Not every one of these videos did it for me, but there are some absolute corkers in the lot.
The black liquid mixture is known as a ferrofluid, and is made up of nano-sized, iron-containing particles suspended in water or an organic solvent. When a magnetic field is applied, the ferrofluid puffs out, creating some alien-looking shapes and formations.
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.