Google AdWords has released a new reporting feature: the Geographic Performance Report, which tells users where their impressions, clicks and conversions come from. Reporting can be terraced down to the ad group level.
The AdWords blog describes it thus:
Say you sell and ship gourmet ice cream to anywhere in the U.S. After running the report, you find that your ads are doing great in Miami, Florida and Phoenix, Arizona, but you’re also finding a surprising amount of customers from Juneau, Alaska. Next step: refine your campaigns. By specifically targeting those locations where your ads perform best you can maximize your campaign’s performance.