I found this fascinating. This guy turns up to a park in Berlin - where the Berlin Wall used to stand, no less - every Sunday with his laptop and some speakers, and hands it over to the crowd who take turns to get up and sing. There are no tickets/entry charges (yet), and no advertising (yet).
It's getting bigger every week by the looks of it. And David Hasselhoff's not even involved!
http://blog.luckyvoice.com/2009/10/berl ... -big-wall/
I wish my neighbourhood had something like this... although I suspect British people might be unable to do it without getting wasted! Has anyone else ever seen regular outdoor karaoke like this?