I encourage everyone to read this article by Declan McCullagh: Q&A with Charter VP: Your Web activity, logged and loadedThe gist is that Charter Communications, the third largest cable operator in the US, is testing a system to capture the URLs you visit when you browse the web, then provide that information to advertising networks through a third party company, NebuAd. They claim this information is "anonymized", but I can't really see how that is possible. If a company wants to target car ads at people who visit many car websites, then the advertiser must know that you have done so when you are shown the ad. Since they have your IP address, they know who you are (or at least have personally identifiable information).While the advertiser may not get the actual web logs, this is a huge amount of information, and I am sure more could be gathered by a clever and systematic set of advertising targets. For each narrow target, capture information on which users match the target criteria when there is an opportunity to show them an ad.The obvious solution is to prevent the ISP from gathering this information in the first place. Any kind of encrypted tunnel, like those provided by the various Anonymizer solutions, will prevent this kind of commercial espionage on their users.