No heroic stories, really, but about a year ago, my wife and I were walking through the neighborhood after dark. An aggressive dog came charging up the sidewalk at us. I lit him up with my Surefire G2 w/120-lumen bulb as he got about 30 feet away, and he quickly changed his tune and backed off.
Just the other night, I used the same light to illuminate the driver of a speeding Ford Expedition who was doing high-speed laps around my block at night. Perhaps he thought I was a cop, but his response was to quickly slow down to a reasonable speed as he passed, and he then left the area.