I like this idea. I don't take nearly enough pictures of strangers... for one, I'm shy about it. Two, I don't want people to "pose," but it feels wrong to snap a pic without their knowledge. So I waffle about it and end up not taking the pic.

I find it's easier to take pictures of strangers at events where photographers are expected to be at. I got some great shots of folks at a war rally a few months ago, and nobody minded I was taking pictures of them.

Of course, you could always go with the voyeur method - really long lens and hide in the shadows somewhere.