I used to play in the subway. If everyone tossed in a quarter, at the end of the day it would add up. It shows you aren't invisible. And it's better than being ignored, or kicked in the head, or worse.
Lately I've been going to all these high schools talking to the students, answering their questions, listening to what they have to say. It has been an incredible journey to be around them and try to give them what my mother gave me.