I had interesting results playing around with simply adding something like the string "/car_insurance" to the end of any given page name..like for instance...
somethingsomething.com/page2/car_insurance
Like if you had a link to the second page on your homepage and could rename it with a string on the end in the hyperlink..then any google ads that show up would be for that exact keyword...but then from what I have seen only 1 adsense box works, the one closest to the top of the page..I don't use this as any adsense I have on any sites is just for the related content and I have no need for other stuff..but I can see where this could be useful and meaningful and surely not harmful if you know your site and traffic types...just an idea..not sure of the possible implications with google so make sure you don't break any rules, but I can't see harm in naming your own page and in not editing their adsense codes..they still detect what to display this way!...Good luck!
k:
Chris
heres an example....this page doesnt exist but just a word is added to the end of the name..notice only the top google box displays "fishing" ads when normally its all magic links..must limit it somehow..not sure..
http://www.chrisangelmindfreak.com/fishing