gary,
here's some info that might interest you. it's from google's investor relations site:
============================================================
"We generate revenue by delivering relevant, cost-effective, online advertising. Businesses use our AdWords program to promote their products and services with targeted advertising. In addition, the thousands of third-party websites that comprise our Google network use our Google AdSense program to deliver relevant ads that generate revenue and enhance the user experience."
===========================================================
For more info go to:
http://investor.google.com/
Or to:
http://investor.google.com/releases/20050421.html
btw - full disclosure

i own GOOG.
-ja