The privacy concerns of this have been talked about endlessly, and I'm not writing to add to that discussion. My question is: privacy aside, how many companies actually have the intelligence to even use such a system effectively? Theoretically, the more information you have on someone, the better your targeting should be. Given this logic, a service like Facebook, which knows a lot about me, should have very-well-targeted ads.
Theoretically.

I mean, come on. This isn't rocket science, people.