they seem to do what you're talking about with adsense
Still hoping for an open-source version though. I find it strange that Google itself doesn't allow this, they would win more money, too.
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.
It's free as it's in beta now - can't find how much it will cost in the future.
In fact, to be a total contrarian, I suspect intelligent design theory can provide such a heuristic for all real world problem domains. The irony is thick indeed.
GAs don't violate No Free Lunch. After all, you're a genetic algorithm...