You may be able to find a plugin that will provide you with a tag or something to use. Either way, you're going to have to find some way to override the default behavior of whatever template you're using.

Opening this up again. What would be a good way of enabling PHP in CSS without breaking everything?

You can use faux columns to fake it. Essentially it entails using an image as the background for the parent container and using three columns with no background to hold your content.

Ah, that was the problem.

Lightspeed had:

AddType application/x-httpd-php .css

In order to allow for dynamic CSS. I suppose I'll have to find another solution or manually insert the headers.

Thanks for the idea.

I believe what you're looking for is to edit the loop on your category page template and remove the the_content() echo in the loop. Replace it with something like <a href="<?php the_permalink() ?>"><?php the_title() ?></a> or something similar.