I use Drupal to build websites. I am a developer at Yahoo! in the Content Match Ad Serving Team (Google AdSense equivalent).
I consulted for a startup (Virtunet) that wanted to monitize its traffic through Google AdSense. I built popquizwiz.com and helpingisfun.com using Drupal for them, and heavily integrated the Ads from Google, AdBrite and other sources. Safeguarding against excessive Ad clicks from enthusiastic supporters was the foremost concern of the client. So, I built extensive click tracking and Ad rotating technology.
At Yahoo!, I work on the Ad Serving technology. I use perl, unix, c++ and no Drupal. DrupalCampLA and monthly Drupal meetups are my sole ways to keep up with the Drupal world.