Once upon a time, when we still lived in Boston's South End, my husband Ted and I served our community as its only little free librarians. Ted built our library out of scrap wood and pieces of an old Nordic Track, with help from his friend Matt, and painted "make way for readers" ducklings on the roof; our neighbor Ken Clark contributed the duck feet. The library stood on our front stoop and anchored the street. It could hold nearly 50 books, depending on size, and the idea was simple: take a book, leave a book. Thanks to its placement near the intersection of a major walking street, our Little Free Library turned over nearly one quarter of its contents every day, and any children's books we were lucky to get disappeared almost instantly. We ran the library for three years, until we sold our house. Another neighborhood group adopted it, repainted it, and moved it a few blocks away. There are now more than 150,000 Little Free Libraries worldwide, in more than 100 countries. Ours was #24,688. When you're out and about, pull up the map on the website, and search for them on your travels.