Golden Rule #4: Stay on topic.
Most groups have at least one person who tends to go off on a tangent or tell irrelevant* war stories during meetings. Whether this is the organizer or one of the participants, all meeting participants have the responsibility of gently guiding the meeting back to the substantive agenda items.
*Note: Not all storytelling is bad; storytelling can be very useful if it is being used deliberately as a mentoring or teaching tool.