I bought Snail Mail, by Michelle Mackintosh, due to this post in Rose Tinted Crafting. Hannah wrote a long review and posted some pictures of the book, so I refer you to her post.
I just want to add that the book is a pleasure to see. Even if I had already tried most of her ideas, I found some inspiration. And it could be really a good gift for people who does not know how to start in the world of the creative mail.