if you refuse to allow cookies for third-party content, you run the very real risk of breaking that third-party content if it needs cookies for it's functionality.
your suggestion to add a referrer-type tag to the cookie store is interesting and I think it would be a very good thing for someone to try implementing.
however it will break some legitimate uses as well as the people you are trying to break. you won't see this breakage on most small sites, but on large sites that spread functionality across multiple URLs you make it will break portions of the site that are common.
Posted Aug 15, 2009 20:17 UTC (Sat) by Tobu (subscriber, #24111)
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The sites I could see being broken by this are domains that maintain user sessions across tlds, like google.tld and lastfm.tld . They could use redirects to transfer the session between the .com domain and the country domain. Most sites that run analytics or ads via just a script tag wouldn't bother.