NandiBear.com is a website where books can be tracked as they travel the world. Just print a passport sticker and affix it to the inside cover of a book!
Getting a passport for books which you're gifting, donating to libraries (or elsewhere) or giving away anonymously (e.g., leaving a book outside somewhere) is a thought-provoking idea. You may be able to see where your books end up and the new owners throughout the years and maybe even a bit of international travel.
Nandibear (Nandi Bear!) passports should also be used for books which you intend to keep for yourself. Someday (perhaps many, many years down the road) your books may end up in new hands. Great also for tracking down lost or stolen books. Passports never expire, they are good forever!
I know you're eager to start adding books to the site, but first things first— What is a Nandi Bear? Read more about Nandi Bear — What's this?