If your ad targeting isn't good (many unrelated ads) you might first try tightening-up the content and/or the information in your meta tags so that it's more specific in regard to the ads you want to show to your visitors.

Another approach for a lot of wayward ads is to use the section targeting commands to get the crawler to "focus" specifically on the content you want it to. This can take a few days or week to show any affect, however.

Section targeting information can be found here:

[google.com...]

If there are just a few ads that are poorly targeted, you can put the URL (only the 'example.com' portion is needed) of the offending ad (found by using the AdSense Preview Tool) in your Competitive Ad Filter (under AdSense Setup) and within a few hours the ad will stop showing.

Chapman

[edited by: Chapman at 3:57 pm (utc) on Oct. 23, 2006]