phpAdsNew - A free ad server for your site
If you offer advertisement on your site, you might take a look at this program:
phpAdsNew / Open-source ad server
It allows you to rotate banners and buttons, pop-ups, text ads, DHTML banners and more. It also lets you track Flash banners, which can sometimes be a problem.
It’s targeting and capping is also pretty thorough. You can track by keyword, IP address, domain, weekday, hour of the day, language, browser or operating system.
You might check it out if you’ve ever considered such a thing. If you like it, they ask for a donation.