Last night on ABC's "What Would You Do," in the segment about how people react to collapsing people, there was a homeless woman. In some of the shots of her I couldn't help but wish her character could be strikingly preserved in a portrait. The first word that came to mind was "powerful."
I may be alone in this opinion, but before she did more than stand by and ask people for help, I was inspired.
She can be seen from 4:30 in this video:
YouTube - Linda Hamilton - What would you do?
And I know this is played to death, but here's also a video of simple headshots by Clay Enos. He shows how he goes for a powerful portrait, and defines it fairly well.
YouTube - Street Portrait Photo How To
I'm neither suggesting setting up a white sheet in a street, nor asking a random person with character for a portrait. It may be your route, but I'm just trying to get some gears turning.