Best PPC Ad Location?

If you have Google AdSense or other PPC advertisements on your forum, in which location have you experienced the highest CTR? Which location has yielded the highest earnings for you?

 

Have you seen the Google AdSense Forum heatmap?
https://www.google.com/adsense/support/bin/answer.py?hl=en&answer=17954

 

Yeah, I've seen that, but I've actually seen some vB/AdSense guru directly contradict that heatmap.

I'll see if I can get him over here to post a few of his articles.

 

I've seen one of his videos, but haven't had time to sit down and watch them all yet. They're at:
Hendrik Kleinwaechter on Vimeo

 

His articles and such are on his blog, as well: Successful Advertising