Debra,  I enjoyed your article especially since it closely aligns with many of the roles I've played over many years, none with a leadership title.  Where i see a strong example of this topic is in training. Seasoned employees often take up the role of guide and mentor for the novice or less experienced.  Leading without official authority means you have garnered the trust of individuals. And in many cases you, yourself have earned the honorary title of goto person.