Many founders want a book deal. Not many get one the way Mike Gustafson of the Ann Arbor, Michigan, bookstore Literati did. When the shop opened in March 2013, the co-founder set an old, light-blue Olivetti Lettera 32 typewriter in the basement, amid the travel guides and cookbooks, with a single blank page in it.

Customers began typing, anonymously, reveling in an odd public intimacy. Some messages were poignant ("She needs help. I really want to help her. But I don't know how"). Some were absurd ("My mom used to be a mime. I just found out. She never mentioned it"). Some proposed marriage. It became a thing. This spring, Grand Central Publishing made it a hardcover: Notes From a Public Typewriter, which collects 123 notes from the thousands Literati customers have pecked out. Postbook typewriter communiques can be seen on Instagram at @publictypewritr, an account we like so much that we just made it our #IncSocialSpotlight. (Really. That's a thing, too.)