I often swap books with friends and coworkers, and try to obsessively keep track of where my books are to ensure I’ll get them back. It would be amazing if I could mark my “Owned” book as being out “On Loan” and to whom. Ideally it would include a lookup to other Story Graph users. Then I would encourage all of my book swap buddies to sign up for The Story Graph so we can track not only our reading, but our loans to each other.