I'm getting site-targetted ads on my site with a very low CPM of around $0.20. I'm not sure who is targetting my site because it is only a couple percent of the overall advertizing.
Can I find out who it is? Or is there another way to stop this?
site-targeted ads usually show up when the value of your page drops... if you are getting 'em every day, however, consider the reasons why your average page value remains low.
is the page design bad? or maybe there aren't any advertisers in your field? etc.
opt out by writing Google. If your content is broad (on more than a narrow subject) you will get mistargeted ads through site-targeting or at least not as good.