Last night I released the first version of Cleanr, a Drupal administration theme that tries to make the interface more simple and clean. This theme was mostly created for site maintainers, usually clients that don't know much about Drupal but need to work with it everyday. The main goal is to improve Drupal administration UX the most I can. Here are some screenshots of the first version of the theme:
_Administer page with an error message_

_Collapsible fieldsets_
I'm doing this on a theme, so no need for a module here. What I need to do here is override (the "Drupal way") the theme_links function and that's very easy on a theme, we just need to go to /includes/theme.inc and copy the theme_links() function. Then we can just paste it on our template.php file but we change the function name from theme_links to MYTHEMENAME_links.