Hi,
Do you mean just site map or Google site map?
For the first option you can use the site map web part - it will generate a site map menu for given section of the web site (according to the web part properties). Or, you can use a repeater web part, set it up for given location/category and the transformation output will be in XML format or whatever you like.
For Google site map, please see this
documentation whether it will fit your need or not. If not, you can again user repeater web parts in given locations (e.g. you will have a sitemap document for each location) of your site to generate the output you need (in fact, the default Google site map is using repeater as well).
Best regards,
Juraj Ondrus