e1a3a9e2_eb_Design_Blog_Web_Design_Blog__Example_
[Type:] Matrix [Important:] Strive to always give the visitor a way to see where he is in relation to the current area/section/cathegory as well as the root. [Example:] 
A matrix structure can be exemplified by an Excel spreadsheet. You have reference points at the top and at the side, where the points meet you place content or links. Sites that use one horizontal navigation for main areas and a changing vertical navigation for each area are using a variation of the matrix structure. This is also useful for navigating lots of small bits of content, research material for example.
What's behind the great designs? - Web Design Blog Web Design Blog
Example: