I carry a book with me to read when waiting in line or the first one to show up to things.  To keep my place, I need to use a bookmark.  Most of the time I use what ever paper I have at hand.  Scrap of paper, candy wrapper I made sure was clean, an envelope.  Once I read a book with a dollar bill as a book mark.
The other night I went to a dinner party.  I knew I would be early and carried my book in with me.  I sat down and opened my book, and pulled out the grocery receipt that was the book mark.  Then as people started showing up I put the receipt back in the book.  That's when I had a thought.  I bet some of my photos would make great official book marks.
The next day I looked through my photos and found some that would be perfect.  To test how they would look I tried to get them the right size and took them to my local printer.  The guy at the photo department watched them come out of the printer.  He turned to me and asked if I was printing things off the internet.  I told him no they are mine, and asked if he meant they were that good.  He really liked the one with the squirrel looking into the camera.  It made my day.
So I will be offering them in the Etsy shop.