While skulking around YouTube, I came across these two gems of street performers in Tokyo's Yoyogi Park, and while neither of them are really my kind of thing, the bassists in both of them just blow me away. I've seen a good deal of street performers in the US, and they're pretty impressive too, but it's generally the guys who have horns or string or more "exotic" instruments that are the best. The conventional rock instruments set (gtr., bass, drums) tends to be more mediocre.
http://www.youtube.com/watch?v=OdMMn9f-7Kw http://www.youtube.com/watch?v=QhpvH0EXyt8
Sound's not that great, but you can still get the idea.