Despite sending out 175 messages a month, the 800-odd Critical Mass listserv members somehow never engage in Internet shorthand, name-calling or even petty bickering -- three staples of the mass e-mail genre. Founded in 2000 by Meridith McKinley, an arts administrator, Critical Mass describes itself, HAL-like, as "a nonprofit, self-formed visual arts collaborative dedicated to promoting, enhancing and initiating contemporary visual art in the St. Louis region." But in truth its reach is much broader, extending into the realms of theater, music, film and everything else marginally artsy in the STL. From reports on guerrilla puppet shows to the schedule of the Glass Art Society's annual conference, Critical Mass serves up the best of the local underground in a surprisingly mature fashion. IMHO, anyway.