Ask HN: Have you written a book?

I bet a lot of us have, since this is a group that is inclined towards A) intellectual pursuits, and B) making cool things. I'd be really interested to see what kinds of books we've all made. They don't need to be published through the traditional process. In fact, I'm actually more curious to see creative ways good hackers have gotten their ideas out there.

So, if you've written a book, would you link to it and talk a little bit about what it's all about?