Free PHP Directory Script
http://www.directory-search.org/directory_script.php

Multi-level category system, with unlimited number of categories.

Integrated search engine.

Powerful control panel: add/edit/delete/move pages and categories easily.
Move full parts of the directory (subcategories and pages) with one click.

Semi-automated directory: users suggest urls and you accept/reject them.

IP banning.

Fast loading: the pages are developed in plain CSS. No tables nor heavy
code.

Search engine friendly: include title, keywords and description for each
category. Short querystrings (most search engines will index the directory).

Easily customizable: change completely the directory appearence modifying
just the style sheets.