From Scuba Diving Calculators:
The Simple Classified Script was designed to help promote not just your Web site but also your clients as well. The Simple Classified Script is powerful and yet very simple! You can add categories, listings, prices, banners, newsletters.
This is a full Web site script if you wish. You'll love how easy this script is to manage as well as how well it will promote clients and earn you cash. You can modify and edit the script to your liking as all the source code is supplied. This script requires a MySQL database.