I mounted Planet Bike flashers on the waist band of a cycling reflecting vest. I place them at the forward "corner" of my pelvis - to be seen by cars pulling out of driveways and side streets and left-turning on-coming traffic. It is very clear that drivers see those lights. I rode home once rather tentatively because I had forgotten to put my headlight on. Drivers were waiting what seemed forever for me to pull through intersections that I was yielding, figuring I wasn't seen.
Ben