From the Quotation of the day mailing list, 2010-05-17:
"If 'thirty points,' is too dogmatic, the [sic] I offer you an algorithm: find out the age of the oldest person in your audience and divide it by two. That's your optimal font size." -- Guy Kawasaki explaining his "10/20/30 Rule of PowerPoint"
[ http://blog.guykawasaki.com/2005/12/the_102030_rule.html]
(submitted to the mailing list by Kelly Groves)