When we redesigned lists.perl.org last month we launched with a hard-coded list of categories maintained in static HTML files. All the rest of the data is stored in a well structured JSON file. We're looking for a volunteer who is interested in spending a few hours going through the JSON file and adding tag based categorization to all the lists. This will make it easier for people to find the perl related list they want, plus that modern invention, a tag cloud!
If you're interested, drop us a line at webmaster at perl.org, or even better, a patch that adds a new "tag" element to every list containing a comma separated list of tags.