If I'm reading a book, I can remember what page I'm on. It's hardly a superpower or a talent, barely even worthy of being called a trick, but I find it a slightly useful propensity - reading just before I go to sleep I wake up, pick up the book and think "ah, I stopped at page one hundred and forty seven. About halfway down". It saves a little skimming, a little re-reading, the odd accidental spoiler. And while I know that technology as basic as a bookmark - for which read absolutely any scrap of paper that happens to be lying about - would do the same job, it amuses me to be able to do it.
When I first got a Kindle at the end of last October (a kind parting gift from my lovely colleagues at Northcliffe) there was a lot about it I liked. The thing I disliked about it - and I disliked it viscerally, almost as a personal affront - was that my my utterly trivial mental trick of remembering page numbers had been rendered even less useful than it was before. The Kindle knew what page I was on. I need never remember a page number again.