Lunar Magic is a level editor I created for Super Mario World (SNES). It's the first and, as far as I know, the only level editor available for this game. I began looking into making an editor for it shortly after releasing the SoM VWF patch, mostly on a whim to see how hard it would be. It wasn't intended to be a long term project, but things would turn out otherwise...Link (Thanks, Mark!)
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.