Authored by Arne Brachhold in the early days of the Google SiteMaps release by Google. This plugin is so famous that almost everyone who is aware of the importance of the Search Engine Registration, listings and rankings uses it these days.
I feel this is one of those plugins which makes wordpress the best among the blogging tools.
I have just started using it. But I was using Google SiteMaps since its lauch in the first week of june 2005 for many of the sites that I work on
Being a wordpress plugin and giving 100% support to the wordpress blog, the coolest thing about this plugin is that we can also add pages that are not generated by wordpress. That means if you have a page like http://www.mydomain.com/flash/index.html which is not generated by wordpress(http://www.mydomain.com/blog/), you can add this page too in the plugin’s admin panel and the plugin pings google via google-pings telling the changes in the site.