Ari Stathopoulos

A clean, minimalistic administration theme inspired from the new customizer look of wordpress 3.4.1 
It’s pretty basic and adds a css file to your administration.
Since this plugin was created I have used the knowledge that I have acquired to build the bootstrap admin theme, which I would recomend you use instead of this one. 
You can get it here: https://wordpress.org/extend/plugins/bootstrap-admin/
This project was built for the http://magazi.org network of stores.

Magazi Admin Theme

A clean, minimalistic administration theme inspired from the new customizer look of wordpress 3.4.1

SimonEbeling

A user-friendly admin theme. Responsive as far as CSS can manage on the core.

Cream6 Admin Theme

A user-friendly admin theme. Responsive as far as CSS can manage on the core.

Magazi Admin Theme vs Cream6 Admin Theme