WordPress Administration Design: Tiger is a very nice CSS modification for the WordPress backend. It's especially rewarding for design-spoiled Apple users.
A useful addition is the following part in the wp-admin.css:
body#wpbookmarklet {
padding: 23px 0 50px 5px;
background: #FFF;
}
This hides the left margin in the bookmarklet. The margin only wastes space in the bookmarklet. Additionally, I also shortened the bg_body.gif to 160px and then reduced the widths of the adminmenu to 120px and 110px for the LI in the adminmenu, and reduced the padding of the normal body from 245px to 175px. This saves some space on the left - I only have a 1024x768 pixel screen resolution, so space is precious.
Update: meanwhile, there is the Tiger Admin as a plugin - installation no longer requires modification of the core files, and the bookmarklet problem is also gone - the bookmarklet now simply uses the old style and only the normal admin is updated.