In his book The Next Story Tim Challies writes:

In 2006, America Online made an epic misjudgment. As part of a research project … the company made available to the public a massive amount of data culled from … the search history of 650,000 users over a three-month period. This totaled some 21 million searches.

Before AOL released the data, they changed all the user names into anonymous user numbers. But it didn't take long before those numbers were linked to real names. AOL realized its mistake and withdrew the data, but the search histories had already been copied and uploaded elsewhere on the Internet.

Challies offers the following summary based on AOL's mistake:

It was possible to reconstruct a person's life, at least in part, from what they searched for over a period of time …. What is remarkable about these searches is the way people transition seamlessly from the normal and mundane to the outrageous and perverse …. One user went from searching for preteen pornography to searching for games appropriate for a church youth group. Others, spurned by lovers, sought out ways of exacting revenge, while others grappled with … cheating on their spouses. Our searches are a penetrating window into our hearts.

Challies concludes with some challenging questions: "What does your data trail say about you? Would you be willing for your spouse to see it? Your parents? Your pastors?"