This actually goes much further than you realize. There are companies buying credit card purchase data and plugging it into a Data Management Platform along with billions of data points a day and using that to buy their ad inventory from the real time ad exchanges. Were talking about mapping a purchase in a store back to a banner ad impression online.
I know of atleast one company actively doing this, and I am sure there are hundreds others.
Thanks Dave - I didn't know the function of a DMP (or the acronym), so that's an interesting thing to learn about. Sounds like there are some real-time data auction houses for advert targeting as well, which is interesting.
I expect the volumes and retention of this kind of data are fairly unregulated at the moment? I certainly haven't heard anything consistent as a consumer about how this data is collected/used (also bearing in mind international considerations in many cases)
well that prob explains how when I purchase some dev screencasts on ruby, I get an email the same day with ruby books. the freakiest however was amazon recommended parenting books 2 months into my wifes pregnancy, before we had even started telling ppl.
I know of atleast one company actively doing this, and I am sure there are hundreds others.