I’ve never seen anything spread so fast in all my life. Google AdSense contextual text ads are everywhere! Many say they are the greatest revenue boon to content-rich sites since the Internet advertising crash of 2001. Here’s my two cents on the subject:
1) Read Google’s overview.
2) Apply to the AdSense program (see button below.)
3) Read the Lanford’s Dollars and AdSense.
4) Read Allan Gardyne’s How to Boost Your AdSense Revenue.
5) Amid all the hoopla, don’t forget programs such as Fastclick.com which serves banners, pop-unders and skyscrapers. I continue to use Fastclick because in some portions of my site they are still performing better than Google AdSense. Test, test, test to find out what works best for you.