Last year I bought some Blu-rays during Black Friday at Walmart. On my way to the car I got an email that the movies I just bought were available to stream through iTunes, Amazon, Google Play, etc. To my knowledge, I’ve never linked one of the streaming licensors with Walmart. So not only are they keeping track of my purchases, they are sharing that info with third parties based on assumptions (I’m assuming email address). I’m sure some think it’s convenient, but I found it really creepy.

I can't find it now, but I've seen a couple of annecdotal posts where people with high credit limits got there credit limit lowered right after using the same card at a Walmart for the first time.

Maybe those people had other changes in their spending/paying habits, but if credit card companies lower people's credits, how do they make that determination to do so?