I found the following of interest from wordspy – http://www.wordspy.com/words/flashmob.asp

flash mob
(FLASH mawb) n. A large group of people who gather in a usually predetermined location, perform some brief action, and then quickly disperse. —v., —adj.
—flash mobber n.
—flash mobbing pp.

Example Citation:
The Internet has spawned a gaggle of new verbs — Googling, surfing and flaming are words most of us are used to hearing in everyday conversation. Now you can add “flash mobbing” to that list.

In recent weeks, New Yorkers have been using forwarded e-mails to coordinate “flash mobs,” or not-so-random crowds that appear and dissipate within a matter of minutes. Is it performance art? The cutting edge of a new social movement? Or just an easy way to flummox carpet salesmen?

To protect the planned serendipity of each event, participants aren’t told exactly what the mob is supposed to do until just before the event happens. For the most recent New York happening on July 2, participants passed around an e-mail telling them to assemble at the food court in Grand Central Station, where organizers (identifiable by the copies of the New York Review of Books they were holding) then gave mobbers printed instructions regarding what to do next.

The result: Shortly after 7 p.m., about 200 people suddenly assembled on the mezzanine level of the Grand Hyatt Hotel next to Grand Central Station, applauded loudly for 15 seconds, then left.
—Maureen Ryan, “All in a flash: Meet, mob and move on,” Chicago Tribune, July 11, 2003

This website may be of interest to you all:
http://brisbanezombiewalk.com/

This is a great example of a not for profit finding a good bedfellow… the charity of choice for the Brisbane zombie walk is…. The brain Foundation. Perfect! And what a way for the foundation to really create a strong fun profile particularly with the Gen Y and Hen X groups. Nice one.

http://www.zombiewalk.com