I've used the Color Schemes in Ultimate Branding 2.0 to create a set of custom admin area colours, but there are some options missing. This may only be applicable to Safari, but I believe there are a few things you could add better colour support for:
- Some WPMU Dev plugin icons need updating to show the correct colour in the admin menu and show the correct hover colour as well. Ultimate Branding works fine, but Smush Pro and the WPMU Dev Dashboard plugins both show grey and hover blue.
- At the very bottom of the admin menu, the "Collapse menu" link (and its icon) aren't currently customisable with a colour option.
- The WordPress admin button has text shadow which is blue. This is also currently not customisable, so it looks weird.
- On pages like the Posts page which has an "Add new" button, that's still blue - this needs a colour option to customise.
- In the admin bar, the hover colour for the "+ New" menu, the updates number hover state, and the comments number hover state are all blue (there's also a darker blue for 0 comments). These *also* need colour options for customisation.