So who's behind the Tax Day tea parties? Ordinary folks who are using the power of the Internet to organize. For a number of years, techno-geeks have been organizing "flash crowds" -- groups of people, coordinated by text or cellphone, who converge on a particular location and then do something silly, like the pillow fights that popped up in 50 cities earlier this month. This is part of a general phenomenon dubbed "Smart Mobs" by Howard Rheingold, author of a book by the same title, in which modern communications and social-networking technologies allow quick coordination among large numbers of people who don't know each other. (story)