Althought this topic was severally discuss before, i want it to be put in my blog for my future reference. If you like it too you can refer here as i will be always adding anything related to it.

There is a code to make your adsense ads relevent to your targeted keyword. See below for example:

Used Car


Im not sure will it be able to work on blogger itself but i found that it work prefectly at any website. I'll be testing it to make sure and report back here.

If you would like to know more, please put your browser to go here:
http://www.1stsearchenginerankings.com/2007/01/03/tips-on-section-targeting-adsense-ads/

Updates:
Refer here if you wanted to know doing the same thing with blogger.