If you really wanted to you could do cookie syncing based on IP, but does anyone actually do that?
Each user gets their own profile: cache, cookies, history, saved data, extensions, etc. The only thing shared should be IP address and user agent. (Unless the user infects the profile with a url that identifies them.)
I use this for testing, isolating my facebook profile, and isolating all of my banking sessions from my main browsing window. (Just in case they have a CSRF issue.)
It's just been hidden (and there's no need to set up email).
Anyway, the solution to this problem is dead simple: Do your shopping at work, or at a library.
After the Facebook Beacon[1] and Google Safari cookie control bypass[2] settlements I would have thought legitimate companies would be a little reluctant to push the envelope so far as to explicitly bypass privacy controls.
[1] http://en.wikipedia.org/wiki/Facebook_Beacon
[2] http://www.informationweek.com/security/compliance/google-se...
> legitimate companies
Google is both an advertising company and a product company (and big and famous), and also uses Don't Evil as part of its brand; this why it has a user-friendly privacy policy to keep it honest.
B2B advertising companies, which is, like, all of them, have no need for privacy policies, unless their customers (website owners) demand them. And what website needs to have a privacy policy that impresses users? Googe, Facebook, sure, but cheapdiamondsonline.com?
I use NoScript (most sites disabled) with Firefox. I also clear everything whenever Firefox closes. I exit Firefox quite often. So the best way to track me would be using IP address. And if they don't use those very often, then ... no problem!
I'm not sure why more people don't do this. On any newer computer and decent broadband connection, Firefox startup is almost instant, even if cache cleared, etc. There's very little penalty for restarts, even between individual websites. Certainly easy to do in the scenario in the article, i.e. between visits to online retailers.
About my only reason to trust Chrome for browsing is for the built-in Flash, which St. Steven wisely eschewed. So I only switch to Chrome when I absolutely want to view some silly video in Flash. Which isn't very often.
Maybe another way to deal with this is to set up some sort of Squid-like proxy on a firewall computer?