I like a good em dash, me.
Glenn Fleishman on the war of attrition between primes and quotation marks on the web.
(Initially it required jQuery but I tweaked it to avoid those dependencies and Yuri very kindly merged my pull request—such a lovely warm feeling when that happens.)
Jason provides some instruction in using the correct quotation marks online.
Jessica’s handy guide to writing the right quotes and accents on a Mac keyboard.
The secret life of punctuation.
A handy page for looking up HTML entities.
A humorous comparison of the em dash and the semicolon; but this online setting scuppers the author's wit by using hyphens instead of em dashes — punctuation-derived humour fail!
This article is an oldie but a goodie. I find myself referring to it all the time: "Beating typographic correctness out of (X)HTML: more than you ever wanted to know about dashes, spaces, curly quotes, and other vagaries of online typography."
Trying to teach legibility, one legal document at a time.
The Economist style guide: the "dos and don'ts" section is particularly useful.
One of my 43 Things is to eliminate the grocer's apostrophe. Still... this is a well-reasoned argument in its defence.