Surprised to see amazon here. Mmm. You know if I shop for stuff all of a sudden everyone seems to know. Every website will show me related ads. Now that I think of it..
Once someone in the middle has a copy, the value of their trove of data falls precipitously.
I'm surprised as well that Amazon doesn't use HTTPS, they have a lot to gain by being the only one that knows you're interested in a particular book and not anyone else. It could help them get the sale instead of competitors relentlessly targeting ads against you as soon as you express an interest to their site.