drop-down-menu
Use this css to change the background color of the buddypress admin bar dropdown menus. Enjoy!
#wp-admin-bar ul.main-nav li:hover,#wp-admin-bar ul.main-nav ul li {background-color:#666!important;}
#wp-admin-bar ul li ul { border:1px solid #666!important;}

From http://code.hyperspatial.com