eCPM, or effective cost per thousand impressions, is a figure used to represent how well monetized your websites is. If your eCPM is $1 that means that your revenue is $1 per 1000 impressions - $1 is a low eCPM. If your eCPM is $60 that means that your revenue is $60 per 1000 impressions - $60 is a high eCPM. For Adsense, eCPM depends on two factors; the CTR (Click Through Rate) and the CPC (Cost Per Click). In this article I will discuss my 5 step process to achieving a high eCPM.

Adsense eCPM
  1. Write about high paying topics

    The CPC your ad clicks provide depends mainly on the topic you write about. For example, ads about finance pay far higher than ads about MySpace so if you can achieve equal traffic to a finance and a MySpace website the finance site will be more profitable, although MySpace websites may be easier to build traffic to.

    If you have already created a website on a specific topic you can still write about high paying topics within your niche. For example, if you were writing an article on web hosting using the keywords ‘paid web hosting’ will display higher paying ads than the keywords ‘free web hosting’. Small changes like this in your content can create big changes to your CPC and in turn, your eCPM.
http://all-seo-tip.blogspot.com/2008/05/5-steps-to-high-adsense-ecpm.html