Google Adwords has a feature whereby you can prevent people within a specified geographic radius from seeing your ads. It's called Location Exclusions: If you have a pesky competitor that you do not want to see your ads, consider excluding an X mile radius from their location. There is no guarantee that this will work, as location is often based on ISP locations, but it could be an interesting way to hide your ads from your top competitors.
The company I'd like to prevent from seeing a client's ads is ESCROW ASSOCIATES, LLC <http://tinyurl.com/63759pd> , whose ISP is NuVox Communications <http://www.windstreambusiness.com/broadband-phone-service/georgia.html> (now Windstream). The visitor IP address was 173.221.194.2. Can you figure out what precise location I should block?