A WebmasterWorld advertiser is trying to display his ads on the most relevant sites within the content network so that he can bring his page impressions to a manageable level.
With that request, he also would like to filter out by country (extensions, such as .ru) because he does not want to have these ads displayed on such websites.
Right now, beyond doing an analysis of your raw website logs, this isn't possible. However, AdWordsAdvisor has added this request to a feedback report to be sent off to the powers that be so that this may change.
I don't advertise in the content network, but I'm all for both requests. Go AWA!
Forum discussion continues at WebmasterWorld