I don't know how widely this is known, but I've just noticed the site eventful.com at which fans can "demand" performances by their favorite performers, in specified locations. There is a small group of fans of
the impeachment of George W. Bush, at the moment 709 people in 22 locations, demanding that this performer, who is even more elusive than Spinal Tap, make a long awaited appearance in their various areas.
I suppose if a number of the locals were to pile on there, it could become a pretty popular "performer". Where this goes after that is unclear - the site is supposed to issue an invitation at some point if demand is heavy enough, but I'm not sure how that would play out. Anyway, the site is ready and waiting for your input ...
here
709 isn't enough. Why not 50,000? (Registration required though.)
P.S. I don't know anything about the site itself, but I read the terms of use and I didn't see any obvious problems.