Yves has posted a great tutorial on paragraph rules over at Unzipped. His opening words state, "Paragraph Rules in page lay-out software offer a plethora of design possibilities which are often insufficiently known by the average user. They allow you to quickly and easily create graphic elements that are 'attached' to titles and paragraphs. This means it is virtually impossible that such an element is left behind when text is repositioned, for example when text is added or removed in a text block."