I thought I'd start a new thread because I'd love to see some discussion before the call on the different styles of navigation. In my mind, styles means two different things. First, it obviously means how the element looks. We'll call that visual style. There is another element of style, however, that is equally if not more important: functional style (or how it works).
To me, there are several different types of functional style:
- Traditional nav bar
- Traditional footer
- Search
- Tags and categories
- Breadcrumbs
Recently, I've been very interested in how all of the valuable data being expressed in tags can be used functionally as navigation. The most common example is probably the list of tags attached to every article or post. This isn't using them effectively, imo.
So, tags and navigation. As an example, I really like what The Guardian (UK) has going on in their nav bar:

They've got the higher-level topic, and then you can drill down to nested topics. Delicious, however, is really the service that makes tags functionally stylish. If I'm interested in content at the intersection of any number of tags, I just add them together:

I'm not entirely sure where I want to go with this now but, to be honest, I hardly ever use the nav bar for content any more. If I do, it's to login or do some other activity associated with the website. I get my content through RSS, Twitter, and search, but I feel like bundling tags could be the next big semantic step. Thoughts?