"The most commonly voiced fear is Google's unique capacity to track what we're thinking based on what we're looking for," wrote The Boston Globe. "Google can track every name, place and topic we search. The company can learn even more about people who use Gmail, the social networking site Orkut or another of Google's popular personalized services."
Using AdSense technology, Gmail, Google's free Web-based e-mail service, delivers ads into e-mail messages linked to the topic of the e-mail itself. Google uses a totally automated system to link words to their ads, but still, if this can be done, it leaves some people with the sneaking suspicion that Gmail snooping also could be easy.
The Gmail program has been well received, despite privacy concerns. "Our competitors haven't been able to match Gmail's clean interface and huge power," says Google. We currently offer about 2.7GB of searchable storage for free. We also made it easier to sign up for Gmail by using your mobile phone, while making it hard for spammers to get accounts."