As ad targeting gets better and better, I find more and more intended uses for the ads.
Last year I commented that some friends and I had found the easiest way to be alerted when ski chalets became available at the resort we wanted to visit was to knock up a wiki page with the name of the resort and a few words about skiing, run AdSense over the page and then wait for the relevant ads to be brought to us. As ad targeting gets more precise (and accurate) it becomes trivial to simply design a page so that the right ads come to you. AdWords are not just commercial messages: manipulated the right way, they're a tailored newsfeed about things you want to buy.
Yesterday I found what I'm confident will become another use for ad targeting. Pondering attending a pub quiz, I had a look at some web pages that talked about the pub in question. The ads alongside those pages were all for distressed-credit services such as LogBookLoans, debt consolidation and other financial services clearly designed for what marketers would euphemistically call the C2-D/E audience. This gave me pause. If the ads were targeted correctly (and increasingly they are), perhaps this wasn't the event or the venue for me.
We are regularly warned that our Facebook (etc) pages reveal too much private information about us. But that's just the information we voluntarily put on there. I increasingly wonder, as ad targeting gets better and better, what sort of information people will be able to glean about us and our social circles from the sort of ads that targeting systems choose to appear alongside our profiles.