1. At my earlier post here,I had given a one line info on Zombie cookie-The cookie that recreates itself once deleted.Now just read about EVERCOOKIE at a veri good compiled site at http://samy.pl/evercookie/
2. Evercookie is a JavaScript-based application which produces zombie cookies in a web browser that are intentionally difficult to delete.
3. More at http://samy.pl/evercookie/ with good FAQs