Is there a minimalistic admin theme that works with WP 3?
Adminimize looks nice, but isn't compatible with 3.x.
Here are 2 simple solutions:
Admin themes are not that widespread and rarely talked about... I use a mix of plugins for styling the admin.
This one is surely one of a kind to reduce the admin to... its minimum (!).
After updating, your custom option will appear in the list of options.
Recently, I came across two cool pieces of work from the Wizard of WPSE, Herr Thomas Scholz.
Customize the CSS to give your own flavor.
Speed up the admin menu
This snippet is not about UI, but UX. And rocks:
Style the admin menu
This couple of plugins will do an uplift in the menu:
Finally, my own plugin, Many Tips Together, deals with lots of manipulations of the Admin area. I'm about to release Version 2, with a much, much, cleaner code and many new features (for example, I'm including @toscho's themes and the HoverIntent code).
I know there are some out there but since wordpress 3.0 is fairly new i do not think people have been wanting themes as much for the back-end. If you are decent at css you can try and make your own based off of either Adminimize or the current backend. You pretty much just want to get rid of most of the images, scripts right?