A really good article exploring the usage of the data google collects (and even goes so far as to imply they've been lying).

In August, The Associated Press published an investigation into how Google handles the data it collects, following a curious discovery by a graduate researcher at U.C. Berkeley. For years, the company has allowed users to control their “location history,” which stores a detailed record of where they’ve been, based primarily on their activity in Google Maps. This, the researcher suggested — and The A.P. confirmed — did not work as advertised.

Hmm....

We’re often aware that Google is logging our whereabouts.

Indeed.

The overwhelming volume of this information demonstrates just how deep, and inescapable, our relationships with the company have become. And it can be sneakily transformative. To see months of your own search history repeated back to you in list form is to suffer a strange mixture of your most mundane and anxious — and largely forgotten — moments.

Patt leaves his on. “For me, it’s the story of my entire teenage years,” he said. Where I saw a surveillance file, he saw a biography. Google was the author of both, but for now at least it was interested in neither.

For now... until you piss someone off. Then it's fair game time.