www.adsenseaccelerator.com is there, but personally I did'nt use that yet, I'll do in another manner that is, just search for adsense high paying keywords in google and get a list, (most of them are not updated), but you can get an idea what are those high paying keywords, now if you have adwords account login and go to tools-keyword tool and enter a keyword and select Cost and Ad position Estimates in the drop down menu and search, you can get the latest PPC of that keyword and also related keywords.. hope this helps..
So that you can better optimize your site content with high paying ads, as above said method try a search about your content keyword and sort by high paying CPC in adword keyword tool and use those keywords on your existing contents.. Better Keywords... Better Earnings..
Ironically by targeting high paying keywords you are likely to earn a lot less that if you just wrote normal natural content simply because ranking well for high paying keywords is going to be near impossible.