Seen in this week's Post Secrets:
I've thought there was an unusually large number of checkout receipts left in books, and maybe this is why. Although I usually keep the things I find around the library, checkout receipts are one thing I always throw away.
But what if we did offer some sort of in-book messaging? Maybe a sticker with a link to the library's record of the book on LibraryThing or Goodreads, telling people they could discuss it there and meet other people who liked it. Or better yet, remind them to write a review in the library's catalog, along with an opt-in social feature (I wish we had that functionality, but maybe soon).