When I was looking in Google's Webmaster Tools to verify a new sitemap for one of my clients this morning, I observed that there are now a number of additional sitemap options available for submission.

Previously there have been options for "general" sitemaps and "mobile" sitemaps, but now there are some newer ones too:

Code Search Sitemaps
Geo Sitemaps
Video Sitemaps

So what are these doing, and why would you use them?

The code search sitemap help users to "find function definitions and sample code by enabling them to search publicly accessible source code hosted on the Internet" - so you tell Google about Public Source code that you are hosting and this can enable it to appear in Code Search.

Geo Sitemaps are to help users to make content searchable in Google Earth and Google Maps. This allows you to tell Google where to find something on a map without them having to find it from another source. These currently support the popular KML and GeoRSS formats for specifying this content and they are looking to support other ways in the future.

Video Sitemaps help sites to get their videos listed in Google Video search - at the moment they aren't promising that submission will result in a listing (although the same goes for all their other listings as well), but this is a great way of getting your video content into the search engine listings.

It will be interesting to see what types of protocols they add in the future to Sitemaps and how they improve the ones they are already using.