Some years ago I stumbled upon the book New Approaches to Medieval Communication. The book’s haunted me for years now. Or, to be more exact, I’ve been haunted by Mary Garrison’s essay “Send More Socks”: On Mentality and the Preservation Context of Medieval Letters.” I was already knew that archeologists had found rune sticks with messages like “Come home now” (found in a tavern, no less), but in this article I learned about the use of birch bark texts in medieval Russia. From, I found Дизайн и техническая поддержка, a digital repository of birch bark texts. It’s worth a look.