The official Moodle demo site has a pretty slick new theme (featuring drop-down menus and a spartan, but really sharp color scheme). Check it out!
http://school.demo.moodle.net/ while I’m not sure what theme it is specifically, but you might accomplish something similar using the Creatif theme with a white custom background (or no background).
Update: as a commenter kindly pointed out this is actually the “Arialist” theme which is included with all of the other great Moodle 2.0 themes.
