Agami Creative
Designers sometimes use tooltips for their navigation. However, tooltips and aqua are quite an unusual combination.
Whitehouse.gov
A perfect example of how one should organize huge amounts of content into clear and easily distinguishable sections. Also, excellent design of the drop-down menu.
AppStorm
AppStorm is a new website by Envato. A jQuery effect is used to create an excellent and very usable drop-down menu.
Eric Johansson
Eric Johansson, a designer from Sweden, uses tall vertical blocks and images for his navigation.
Coda
This conveniently located menu has a beautiful hover effect. The sub-menus are consistent and include every item.
Dragon Interactive
Dragon Interactive has a colorful jQuery-based menu with a great effect.