This summer, my son and I are taking a trip to Oregon. He and I spent a ton of time online looking at hotel reviews and maps and room rates, and we finally narrowed it down to this one great looking hotel. We browsed the hotel's website for a while, and we ended up booking our stay on one of the travel aggregator sites. The next day, and for quite a while beyond that, I noticed that in my Google Reader feeds, the advertisements at the bottom of each entry were ALL FOR THAT HOTEL. In other words, the internet, or more specifically, Google, had been monitoring where I'd been browsing and had honed in on the place it thought I wanted. Google had personalized the ads just for me.
That idea is not a comfort to me.
Nor is it a comfort to Eli Pariser, who discusses this very issue in the following TED talk. Watch it and squirm: