Google are facing a giant backlash about this with their personalized search results. Google can provide universally-relevant results to all of us easily, but they were (rightly?) afraid of being out-competed in the "niche-of-1" market. For now, their personalized results are stuck in the uncanny valley, just like advertisements are.
[Also not the OP]
One of the ways you can see this in action is with re-targeting. If you visit somewhere like SEOMOZ or www.shoesofprey.com (with cookies enabled) you will start seeing advertisements for them pop up everywhere. It feels strange (especially since I am a long way from teh target market for something like Shoes of Prey -- checking them out as an interesting Australian startup does not mean that I want to buy a custom-built pair of high heels)
I'm not entirely sure what you meant to say in that last sentence, but I know you didn't mean to say "uncanny valley". Stuck in limbo, perhaps? (whatever that would mean)
Maybe "creepy" - I search for an item, and Google shows me ads for that item for the next month; I keep searching for that item, and Google learns to tailor its results to what I want.
Some people find this useful. Other people find it creepy.
I find the creepiest search ads are ones that direct me right back to the context of a site I was already surfing on a few minutes earlier. E.g. I was looking at the Amazon Sci Fi book section for example. Then, via google adsense on some other blog page I'll now see an adsense ad for Sci Fi books on Amazon. This has happened to me a couple of times now.
