the right ads in the right place

Have you ever noticed that marketers have been using social media for pushing their products? All social networking sites, especially popular ones like Facebook have a host of advertisements on the side, all fine tuned to your local area, so that you can click away for getting the safest acne treatment or getting class photos printed on T-shirts for your reunion and so on. I only noticed these ads quite recently. Well, since I don't go on to Facebook much, I'm not likely to notice them earlier, am I? The thing is that I was quite impressed at the reach of their local ads. I mean, some were of places that I'd actually go to, but hadn't known where to find them. So it's a job well done for the marketers and SEO chaps.