Not to scare anyone, but if I were a casino, in every promotional email or hotel confirmation email I sent, I'd send down a cookie with every image in the email from server X that is unique to the recipient. Since I know who I am sending emails to, I can associate each cookie with a specific person in my database. Then I'd come to forums like this, and make posts with some sort of graphic in them also hosted on server X...even an invisible graphic (which is possible to do in this forum - you can add any remotely hosted image you want). Even a simple "Great post!" reply with the invisible graphic in a popular thread would do the trick. The cookie is automatically sent to server X whenever any file is requested from it, along with referrer information (the URL of the page where the graphic was posted).
Then, anyone that views a thread with my graphic in it that has a cookie from a promo email would be instantly flagged in the player database. They would know your specific identity and what forum(s) and thread(s) you were viewing. Offered as a service from a third party, only 1 casino would have to participate, and others could simply buy lists of players that are in this and other AP forums once a player has been identified. Reverse analysis is also a trivial matter; the graphics in the threads can have a cookie sent with them as well. If you then at any time in the future open an email from a participating casino, the cookie you picked up from the forum is sent and they know that you have visited an AP forum in the past, even if you weren't even a member of their players club at the time you viewed the thread with the graphic in it.
Just saying its technically possible, and easy to setup...a good programmer could do it in a day. Perhaps it would be better not to allow remotely hosted graphics on a rather sensitive forum like this. Hopefully they aren't already doing this. If I were the admin I'd do an audit of all external graphics already posted...if they are already doing this, some people on here could already be facing some issues. Privacy is an illusion.
BTW, this is another good argument against playing rated...Lol.