As the maintainer of an open source proxy (Seeks), I'm playing with randomizing the last-modified header, on demand. The randomizing procedure is triggered by a

As the maintainer of an open source proxy (Seeks), I'm playing with randomizing the last-modified header, on demand. The randomizing procedure is triggered by a regexp over the requested URL. Does anyone here know if (and where) a useful list of websites that use such tracking methods has been compiled ?