I was working on a sitemap for my site last night. It's basically a table with the links on the left and a one-line description on the right. Nothing too fancy. Most human visitors will probably never see it.
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When people speak of site maps generally what they mean is an index (like Intel's) of the sites pages categorized under their main headings so they can quickly find a particular page without searching, or navigating a menu structure.
A true sitemap would be one that showed all the internal interconnections between sections and pages of the site, as well as a notation to offsite links. Few if any site do this, though I recall seeing one or two over the years. The reason is that such a map is time consuming to create, requires a major effort to maintain, and is generally useful to the site's maintainer, and the curious, than it is to those actually using the site.