I would upload my Backend Theme, but unfortunately there is one file which wasn't touched by the core team, so the skinability is not really fulfilled.
It is the "page tree".
So I am using a "hardcoded" pages/index.php file in order to fix my needs.
Once this part is skinable I will provide a full Backend Theme Package to the community.
In fact I have more than just one Theme.
I also like Argos Theme very much, because it is more comfortable in some areas. (I do not like the icons this theme is using very much though.)