Compare Google Results from Around the World  in Google Operating System blog has a nifty link to a mashup for Geotargeted search comparison  

"Google uses geotargeting, so the results from different countries (and even regions from the same country) might be different. For better results, select a data center instead of using google.com. My only complaints are that the site is pretty slow and it doesn’t have an extensive list of countries."

Tested this site out and it looks like it works well.

I can see a metric where you look for your listing in the top 10 results of as many countries as you can, the more the better.