After playing Google Monopoly for awhile, I realize that this is the most subtle yet invasive form of data mining that I can think of. But it seems so cool. I just started, obviously.
Seriously, what could you do with the data that you can collect here? The possibilities are almost boundless. Don't get me wrong - this dataset by itself is fairly harmless. But, combined with other forms of similar datasets, much more can be discovered. If you're interested to know more, I'll either write more at some point or you can hire me for a consulting gig!
I could probably go off on this topic, but I'm busy buying properties and contributing to something sinister. Don't worry, I'm pretty stocked on tinfoil.