(01/08/2013 01:45 AM)Tetris999 Wrote:  Wat. Da. Fuq?! What data mining is this? To what extent do they use data on the internet to do these things? What's being monitored?

Considering that tracking is pretty much where Facebook derives its revenue from, you can be sure it's pretty extensive.
I mean, stuff like graph search has shown what they can do, and this is publicly shown.  Imagine the stuff they can do behind the scenes.

Every single Facebook Like button is tracking you - that is, merely seeing the button sends info back to Facebook that you visited the page.  You can try having multiple accounts, but I'm sure FB have methods of triangulating that it's really the same person (IP address matching, browser fingerprinting, cookie tracking along with behavioural browsing analysis etc).
Google probably do mostly the same thing - I mean, so many sites have Google Analytics installed, reference the Google CDN, their "+1" button, ads, Chrome, Google DNS and of course, Google search.