Application server - User interface

I'm starting to get a fairly complex web application with a lot of
modules and not all of them are interconnected but all serve the same
intranet users. I have delayed doing much with the overall user
interface and using a modified version of the basic layout structure
from AWDWR and that has served me well so far.

Yesterday, I started playing with 'tabnav' plugin and can see at least
some instances where this would be useful and am thinking that this may
be useful for the overall user interface.

So I'm thinking that I am going to have to create some type of menu
structure, perhaps pop-up menus via javascript and hidden buttons or
just drill down tabs and I'm wondering, if anyone can refer me to some
examples of sophisticated Web 2.0 type interfaces that provide
interesting examples of web applications with a lot of module entry
points. This is likely more of html/javascript/css than ruby solutions
but ruby based solutions that integrate javascript and css are of course
of interest to me.