Let's assume that the paranoids are right and Google is tracking everything you do on the Internet and they know all of the illicit and embarrassing sites you visit. Don't sweat it. As Matthew Kelly says, you're not that original. If they started using that data to blackmail or coerce people, they'd immediately devalue the information until it's gradually worthless by the sheer number of people all committing the same sins. By the time there are 150,000 people who've been caught visiting sports gambling sites at work, #150,001 is going to shrug his shoulders and go back to whatever it was he was doing.
Google is a threat? Meh. Your conscience pangs comes from inside, not from some Internet voyeur.