Category navigation

[momatej]

Is there already something pre-made for category navigation via JSP or FreeMarker?

For example I have bunch pages that I have to organized into categories. And be able to still add new categories and pages. I'd like some solution that would allow me to define panel on left side of each page that would display something similar to eBay's navigation. I use SiteMesh Decorator with FreeMarker and have an idea on how to do it from ground up. I'm just wondering if there is already reusable logic somewhere out here.

[momatej]

This just sound like something very simple. I'm looking for more complex situation where I will be able to do constrains on the categories selected. More like filter.
I don't want to be highlighting anything :
http://www.iteezy.com/i.html?q=test

Notice the categories on left hand side. What I want to do is replace that menu each time I click on subcategory with the list of the subcategories.

I started to work on some stuff but any advice would be very helpful.