I usually ask when I see someone stopped by the side of the road as well. I carry a pump, patches, spare tube, and some basic Allen wrenches. This past summer I fixed a flat for a girl that was out for her first ride on a new bike. Then a week or two later I ran into a guy at night that was broken down. He had no idea why he couldn't shift. The cable had come loose from the clamp, but he had no tools and no real understanding of how the front derailleur worked anyway. Got him back on his way in about 10 minutes.
Mark