Site Sift Listings

This site itself is a very popular directory and they provide their script running their directory for free. This script is updated constantly. Some of the features are ability to edit/move categories and listings easily, customizable meta tags, SEO Friendly URLs, Integrated Payapl payment gateway, offers different kinds of submissions, database backup, link details, allows coupons, IP banning and much much more. All for free.
Features Live Demo