If you start making a good amount from adsense, I think Google take an interest.

I was contacted by Google and offered an "Optimization" - basically they looked over one of my websites, and moved a few things around, changed a few settings on the adsense, and emailed me back some mockup jpegs. They just said "We think this will work better, it's up to you if you'd like to try it" - I did, and it increased revenue... They mailed back a little later to say it looked like it had a good effect etc.

I know it's not an automatic clever machine based system, but it worked well for me.