[HTML] em dash character

I'm having a problem with em dashes. I'm fond of asides set off by this piece of punctuation, but HTML doesn't seem to share my passion. As far as I know, there's no semantic em dash token (along the lines of amp, eacute, and so forth). I've been using the numeric code that often maps to an em dash (151), but that has always been subject to the whim of the encoding scheme in the browser, and lately that's broken for a number of my readers. In particular, Bloglines now renders my em dashes as ? or little boxes with a's in them, or whatever.

So what do other folks do for em dashes? It seems silly to write modern text as if I were still using a typewriter, with -- serving the purpose, but I may have to resort to that if I can't figure out a consistent way to get the appropriate punctuation to show up in browsers et al.

Any ideas?

[Update: I wrote this and then went searching for the answer elsewhere. A good article can be found at http://alistapart.com/articles/emen/. But I thought I'd do the post anyway so that anyone who had the same question could still learn from it.]

This Post was written by Derrick from An Obsession with Food.