I finally created a proper sitemap.xml file last night
It's been a to-do list item for several months now, and I finally got to it last night.
I used the Free Google Sitemap generator from enarion.net and while it took some massaging to get just right, it wasn't all that bad.
One of the reasons I took so long getting it done is it feels like one of those "best practice" sort of things that I personally won't see all that much benefit from implementing. I already get good search engine traffic and coverage (both trending upward,) so I'm not sure how much this will help me. Still it's such a strong idea I was basically compelled to do it as I like to sandbox stuff like that here from time to time in order to get a good sense of how they might work in the wild without putting any client (other than myself) in danger.
If you're interested in this sort of thing and want to know more, check out the aptly named sitemaps.org for plenty of useful information.