This contribution was coded to meet the protocol specification delineated by Google for the XML Sitemaps experimental service.
1) Super easy install - no file edits!
2) Generation of sitemap files for products and categories (separate files)
3) Generation of a sitemap index file
4) Built-in support for large catalogs (more than 50,000 products, categories, or both)
5) Optional file compression per Google specification (GZ format)
6) Thorough documentation for developers! Don't be shy...improve the code if you can.