Smashing Magazine has published an article called, “Mind Your En And Em Dashes: Typographic Etiquette” which illustrates a number of common typographic problems and how to correct them. I’d rate it an intermediate level article but it’s still worth a read if you want to gain insight into the world of typography. At least at the end of it you’ll be able to tell the difference between a hyphen, an en dash and an em dash. Ok, really geeky, but it’ll impress your friends. Maybe.