Improv Everywhere - genius!

Before I say anything about them tho, check this guy out, damn he's brave to pull this off on stage! A trip thru dance from the 60's to the present day, with about 10 seconds devoted to each one. About 6 mins, but worth waiting for the download, I think.
http://video.google.com/videoplay?docid=8919541964498299964&q=genre%3Acomedy

And as for improv everywhere, they are halfway between performance art and the 'flash mobbing' craze that last for about a week a few years ago. Essentially they get a group of people to meet somewhere in NY, then give them a task, and see how the public react.

I can certainly recommend 'Best Buy' 'No pants 2k3' 'Megastore' and 'The Amazing Stuntmen' are all worth trying out to start you off.

http://www.improveverywhere.com/missions.php

I get the feeling although they are working on a DVD, they're really in it to have fun for fun's sake, and that's something to be applauded.