We do this to make a slightly more user-friendly 'edit' interface (less confusing options) on a few sites. The way to do it is to set up your own design, that has the default admin interface as a fall back, e.g. in edit/site.ini.append.php:
...then you can override admin templates as required in that design, in my case commenting out large chunks of the admin interface I don't need my 'editors' to have access to, but still keeping an 'admin' siteaccess for myself and power users.
We take Matthew's approach as well. We even have a default override that we start with on every site. No big changes, but we mainly move the right column to the bottom of the left column so that there's more width available for the main column.
If you have a situation where you just want certain users to only edit certain items, you can even build editing features into the 'public' side of your site by checking to see if a user is logged in, and providing edit links in the template if they have editing permissions.
