Could perhaps talk about what it's like to write a book for O'Reilly based on my experience of writing The Geek Atlas. Or talk about the Analytical Engine project. Or how everyone in London should be using CloudFlare. Or bit banging on micro controllers. Or what I like about Go. Or being a programmer over 40 :-)
I've enjoyed most of your writing, so I'm sure anything that you chose to talk about would go down well. Particularly the book writing or Analytical Engine bits would interest me.
Dropped you a line. I'll come and do a talk entitled: "That'll never work!" about some crazy ideas that I've had in the past (The Geek Atlas, the Alan Turing Apology and the Analytical Engine project) and lessons from having crazy ideas.