WordPress sitemap, sans plugin

What is a sitemap? I'm guessing most of you know what a sitemap is, but if not, here is a basic definition: > A sitemap is an xml file that search engines use to know what content you want indexed and when your content has been updated. Normally you'd use one of the many plugins available, but now you don't have to. One less plugin to load and maintain is always a big plus in my books. So, on with the show. I hope you find it useful.