I created a banner network for a McDonald's Coinoffer campaign. The idea was that everybody with a website could embed a banner on their site. The banners contained different Coinoffer Coin QR codes that the users would scan and then click the banner to go to the next coin. Traffic to the banner network was feeded from the traditional banner networks, so people that embedded banners on their site would see a rise in traffic.
Written in PHP on the Slim framework http://slimframework.com/ and with a MySQL database.
Data Access using Idiorm and Paris http://j4mie.github.io/idiormandparis/
Template engine is Twig http://twig.sensiolabs.org/
Mails sent using Swift http://swiftmailer.org/
Crawling using PHPCrawl http://cuab.de/
Administration interface using PHP Grid http://www.phpgrid.org/