Anything that makes a thank you note more personal is worth including. For example, a thank you after a child's birthday party might come with pictures that the birthday boy or girl colored.   Likewise, a wedding thank you may include magnets or photos of the couple, assuming that it's sent after the big day. In other situations (such as a closing gift from a real estate agent), the thank you might be accompanied by a small gift card or other token. However, keep in mind that while a thoughtful gift will be appreciated, the message is essential.