I have a very young niece who is returning home after a short couple of years living abroad. I embellished this ruler for her mum to add " Play Date" details. She can then bring in a bunch of them to her old school pals.
They could also be used to add birthday party invitations. Dressed up with blank party invitations and sold in sets of 6 or 12, with boy or girl themes I think they would make a great craft fair item. Very easy and reasonable to make.