I do an "on your left" and ding if they don't move over. The people on the bike path usually understand "on your left" better, but pedestrians react better to the bell.

The worst, and I repeat WORST are the ******** who walk in the bike lane on the descent of the NYC bridges. Nothing like going 30mph+ when a stupid tourists decides to abruptly walk in front of me to take a picture. I hate them, and would not feel bad if I clipped them. Theres a reason why there are separate lanes.