Ad management-related web-based apps. Ad serving system that enables publishers, ad networks and advertisers to: (1) serve ads on websites, in apps, and in video players, and collect detailed statistics about impressions, clicks and conversions, (2) manage and run campaigns for multiple advertisers, and from ad exchanges and ad networks, all at once, via an easy to use interface, (3) define rules for delivery of campaigns and ads, including frequency capping, URL targeting, geo-targeting, and (4) track and report campaign performance, including impressions, clicks, click-through rates, conversion rates, revenue, eCPM, and conversion details, like basket value and number of items purchased.

GPixPixel is a FREE yet powerful million pixel script, based on the popular marketing concept. Advanced settings include, among others, the ability to use interlaced images, temporarily take the site down for maintenance and put it back online when all changes are done, and enable/disable blog comments. Multiple payment modules available for pixel purchasing, including Authorize.Net, PayPal, NOCHEX, PSiGates, and others. More are being added all the time. PayPal IPN is fully supported, too!
OSClass is all you need to easily create your own classifieds website. It's a free and open script to create your advertisement or listings site.
Revive Adserver is the open source ad server formerly known as OpenX Source. Revive Adserver enables publishers, ad networks and advertisers to Serve ads on websites, in apps, and in video players, and collect detailed statistics about impressions, clicks and conversions.
Yclas is a free open source powerful PHP classifieds script that can help you start a website and turn it into a fully customizable classifieds site within a few minutes. You can be as creative as you want with Yclas, create a marketplace, job board, real estate, car dealer or anything you want! modify text, customize fields, add users to help you moderate the website and many more features.