Reading Against the Tide of Years, by S. M. Sterling while walking down Market Street. He's read it at least a dozen times. It's part of a three book series set on the island of Nantucket 3000 years ago.
After interviewing over 1,200 readers, I've discovered the beauty and rarity of a given book being read at a given time, instead of, say, packed away in a box somewhere. I've also discovered that I've not only been chronicling the popularity of books, but also the diversity of individuals. What goes on inside our minds is evidenced by and influenced by what we are reading, have read, and the inner dialogs we have with authors.