Paper for our receipt printers is expensive, so we ask people if they need a receipt instead of printing one automatically - which means many people leave the library without any tangible reminder of when their books are due back. I've seen libraries use due date bookmarks, which are also a good idea, but this calendar was colorful and definitely eye-catching enough to be a great reminder (especially for kids) - kind of like a real-world Library Elf.
Here's what it looks like in action:
It looks like you download a pdf, which is nice because you can print out extras if you're a heavy library user. I wonder if you could print it onto some kind of glossy paper that might work like a dry erase board. I also wonder if the seller would be willing to work out some deal with libraries to let them sell these as fundraisers.
Thanks for the tip Lauren.