Hide From Google - Wired How-To Wiki

Some useful tips, if you’re inclined to limit Google’s view of you/your activities

"If you're not paying for something, you're not the customer; you're the product being sold." —blue_beetle, Metafilter discussion.

Google started off the new year by announcing that they will be changing their privacy policies so that they can create more detailed profiles of their users. Starting March 1st, 2012, Google will combine information from user’s Gmail, Google Search history, YouTube, and other services. Prior to this change, Google profiled their users, but restricted the profile data use to the service from which the data was collected.

Because we have come to rely on web services so much in our day-to-day activities, it simply isn't an option to stop using search, webmail, and social networking. But there are ways for heavy users to keep a low profile so that, should Google turn decidedly evil, you won't be completely at their mercy. If you are concerned about the amount of information that Google knows about you for whatever reason, here are some techniques you can use to guard your privacy online.

Hide From Google - Wired How-To Wiki