Frozen in Grand Central
This is all over the web but if you haven't seen it, it's wonderful. Improve Everywhere had over 200 people freeze in place on cue in Grand Central Station in New York.
This is one of over 70 different missions Improv Everywhere has executed over the past six years in New York City. Others include the No Pants Subway Ride, the Best Buy uniform prank, and the famous U2 Rooftop Hoax, to name a few. Visit the website to see tons of photos and video of all of our work, including behind the scenes information on how this video was made.
And the blog entry about it is also really fun.
I read it first, as I do so often, on Mysdirection.