I ran across a fun post today, via Language Rules! The post on that rarely used blog linked to Receding Hairline‘s recent post on common typographic errors (rather than grammatical errors) and how to fix them.
I agree with most of his post, with the exception of the part about dashes. Long dashes — as seen here, and otherwise known as em-dashes — are not being replaced with en-dashes (–). And I understand that common usage, for some reason, indicates that dashes should not have spaces around them, but I don’t understand that. The function they serve is separating, rather than connecting, so I intentionally use spaces around em-dashes here. I rarely use en-dashes, reserving them from when a range is needed (such as 1–2), or some similar function.
I also posted a comment objecting to his ellipsis entry. It’s not really that I disagree with what he’s said, but he has committed a usage error. Most of the time, ellipses should be preceded by a space as well as followed by a space, particularly when the three dots are not placed at the end of a complete sentence.