Ubunchu, a manga-style comic for kids about the joys of running the Ubuntu Linux operating system (this post is being composed on an Ubuntu laptop -- the only OS I've used for a couple years now*). It's a free, CC-licensed PDF, and it's been translated into a very large number of languages, and there are more editions to come.
*Yes, I know I haven't written up my notes on switching to Ubuntu yet. I will, someday.
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.