The Hathor Administrator Template has been incorporated into the core package of the Joomla! 1.6/1.7/2.5 content management system. I designed this administrator template to be accessible using the WCAG 2.0 AA guidelines. These are the guidelines with the broadest global scope and are new enough to make use of modern technology.
One of the goals of this template is to be close enough to the standard 1.6 template that any documentation or training on that template will apply to this template as well. If you help maintain multiple sites or are training people from different companies, having a common interface is important. I have incorporated some usability improvements such as moving the action icons from the right to the left and bringing them into the work area. These make the work flow easier but don't require different training.
Hathor includes a High Contrast parameter which uses an additional CSS file to change the colors. This would make it easy for someone to apply branding to a backend by creating a duplicate of the template and changing the colors in this CSS file.