Ozh’ Admin Drop Down Menu plugin is a really time saver in admin area. And it unclutters the admin view. There is only one small glitch in menu icon aligning, if you have plugins with their own menus. This can be fixed with small code change though…
adminmenu.css.php line 252, change
padding:5px 1px 0;
padding:5px 2px 0 6px;
I tested CSS with Chrome 5, Firefox 3.6 and Safari 5.