Most of these places have a space for you to leave your name, a message of condolence, or a story about the one who touched your life. It means the world to the family to read stories from people who knew and loved him/her. Do this more than once - any time you a special memory comes to your mind, even if it's months or years later, because someone in the family will get a notification from the site telling them that a new message or story has been left.