Change friend's wallpaper V2!
My wife and I are in different parts of the country right now and we have found this to be a great, subtle, way to let the other person know we are thinking about them! I can take a funny picture of the dog and set it to her wallpaper! For the email address, set it to the person who you are allowing to change your wallpaper and a unique subject so it isn't triggered by other emails. So in my case, it is set to my wife's email and the subject "wallpaper".