I have finished making a site for a travel agency. It was a fun project, with a lot of css pleasure.
The navigation part is a good example of using css and the body id tag. The navigation and subnavigation are each 1 file that I include in all pages. So if I have to add a new item to the navigation, only one file has to be modified.
By changing the body ID, the visaul on the left and the navigation change.
www.miratours.be (The website is in Dutch)