One might assume that antique books or historical letters are collected entirely by museums and libraries, but there is a small cottage industry of people who collect and trade these treasures. Little Sages, run by Kara Accettola, collects and sells private papers, old texts, historical notes written on napkins, and offbeat pieces and matches them to collectors who will love and appreciate them appropriately. It's not the most common service, but if one is in dire need of rare books or papers, check out Little Sages.