This guy
here is probably the only one who has a decent idea of wtf is he is doing with adwords adcenter and yahoo and all the information is free, free i tell you.
Perry marshall knows a thing or two about how to use copy and direct mail. Thats the only thing now that i think any business can take from him. Otherwise when it comes to adwords its changing too fast for him to keep up. Especially him not being as technically savy as needed.