One requirement of the CoverYourASP advertising system is that multiple clickthroughs from the same IP address on the same day will be ignored. Another way to stop spiders is by testing the HTTP_USER_AGENT.
This tutorial explains the complete banner ad system used at the site, "CoverYourASP". Database driven, but using Application variables extensively, it tracks impressions and clickthroughs and is fully automatic. Source code available for download.
This two-page article provides a couple ways to build your own banner rotation system for your Web site: Using Microsoft-bundled Ad Rotator component, and Using a custom, database-driven approach.
