These are great extensions developped by a MVP (Gary Lapointe) . The whole package and documentation can be found here : http://stsadm.blogspot.com/ 

The list of the 54 (!) new commands can be found here : http://stsadm.blogspot.com/2007/08/stsadm-commands_09.html 

You can for example use this package to copy lists items as described in this post : http://stsadm.blogspot.com/2007/11/import-export-copy-and-delete-lists.html

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