When I go to a store that has a paint department, I frequently select several of the paint sample cards. I enjoy picking out the colors and dreaming about what the walls will look like when I repaint. As a result, I often have a handful of the cards sitting with me on the sofa.
One day when I was in the midst of reading a book, I realized I needed to check on something. I absentmindedly grabbed a piece of paper to mark my place and went on my way.
When I returned to my book, I was delighted to see that I had picked a paint sample card that complemented the book cover. Now I make a habit of recycling the paint sample cards by using them as book-marks.