Anyone doing typesetting or any design work involving text (print or electronic) should know the name Robert Bringhurst. If you don't, then shame on you. Go to Amazon (or wherever you buy books from) and get a copy of his Elements of Typographic Style. Read it. Learn it. Love it.

After you're through reading it, check out Richard Rutter's work-in-progress, The Elements of Typographic Style Applied to the Web. Rutter has an RSS feed set up for site updates; check out his blog for further details.

(thanks to typographica for the pointer)