Jasna Zmak in Croatia has started this beautiful thing:
letters we wrote to friends after reading "polyamorous love song"
"It was then when I decided this was something I ought to do. So, I am giving this book to you, as a present. I am giving it to you, but on one condition. Or actually two. The first one is that you read it. The second is that, upon reading it, you do the same as I did: you think of a friend who you think might like it, who you think will be a nice addition to our small community, you give it to him/her as a present and along with it, write a letter to explain why you think this person and this book might go so well along. Then you give them the letter and the book, and you forward the letter to me, so I could publish it here.
You decide on the length of the letter, I am just asking for the language to be English so that more people could understand it… and, of course, at the end of the letter you make a small note about this principle so that when your friend is done with reading, he or she can send it to the next person, including a personalized letter, so that this circle could go on expanding…"