The Washington Post recently published an interview with Gus Johnson, an amateur astronomer and the first person to witness a black hole's birth.
Thirty-one years ago he discovered a supernova while working with AAVSO, in the same way many people today continue observing variable stars through the organization. But he got lucky as the sudden brightening of a supernova also heralded the birth of a new black hole. Though not all of us receive such good fortune it shows how a dedicated individual with a sharp eye and observant nature can still make a big difference.
Read the full interview at http://www.washingtonpost.com/wp-dyn/content/article/2010/11/22/AR2010112204869.html.