I'm reading Mr. Midshipman Easy by Marryat, a fine earlier adventure tale in the line of the Hornblower books and, I suppose, Patrick O'Brian. It's pretty fun. It has an amazing literary device that I've never seen before and must have dropped out of favor sometime in the last 200 years: in the middle of Chapter 21, the author just leaves off telling the story, and starts talking instead about how great his other books are and implying you should maybe buy some of those as well. After a few pages of this he gets back to the story. I hate ads with a deep and irrational passion but this was surprisingly ok, even delightful.
@jason Cervantes takes a digression in one of his later Quixote stories to have him beat up a rival author who had been publishing unauthorised stories.