Site maps are just html pages with all the links right? I've never made one on an actual content site, it's always been the automatically generated wordpress ones. Just making sure that there is no special logic behind it other than containing all the links.
sitemaps are most commonly in xml format, use http://www.xml-sitemaps.com/ to generate a sitemap the site is free.
There are both xml sitemaps and html sitemaps. The xml is mainly used for the SERPs and html more for user experience and also internal link popularity.
Sitemaps XML format This document describes the XML schema for the Sitemap protocol. The Sitemap protocol format consists of XML tags. All data values in a Sitemap must be entity-escaped. The file itself must be UTF-8 encoded. The Sitemap must: 1- Begin with an opening <urlset> tag and end with a closing </urlset> tag. 2- Specify the namespace (protocol standard) within the <urlset> tag. 3- Include a <url> entry for each URL, as a parent XML tag. 4- Include a <loc> child entry for each <url> parent tag.
I just seen a video with Matt Cutts, he said its best to have both, but if you had to choose between one or the other, he said an HTML sitemap will get you the most traction.