We released the first version of JM GSitemap plugin.Its functionality was initially part of JM Canonical plugin (for testing and saving time), but now we moved it to separate plugin.
With core plugin, you have no option to change the category, but it was used without user see it.
More instructions about HTML sitemap.
Yes, there are plans for further extending, but at first JM Canonical plugin must be cleaned more and we need to do something with metatag plugin.
This plugin is free; just it's download is limited to user subscribed to class JM Canonical plugin (or something like that).