Add tags to menu -OR- add category to pages

Is there a way to add tags to the new menu system in WordPress 3? Or alternatively, since categories are already in the menu system, is there a way that I can categorize a static page? I’d prefer to find a plugin rather than hacking the code, but I’ll do what I have to do.

This is the reason I’m asking: Let’s say, hypothetically, that an…er…friend of mine wants to set up a site to sell ukuleles. I…I mean…he…could set up a static page for each model, then tag (or categorize) by brand and type (soprano, tenor, etc.). The menu system would make it easy to set up a list of brand tags or type tags (or categories…whatever). Then when I…er…he posts a new item, he could simply tag (or categorize) that page, and it would automatically show up when someone clicked the relevant link in the menu.

Any thoughts? I found a plugin that lets me tag static pages, but I can’t figure out how to get tags to show up in the menu. Unfortunately, since “tag” is used to describe HTML code as well, I get a million hits when I do a search.