Borloz.com

It seems that someone has figured out a clever way to check up on website visitors to see where they’ve been - specifically whether or not they’ve been to competitors’ sites.

Of course, it’s well known that you can grab the referring URL via PHP, ASP, Javascript, etc., but this only works if the visitor came directly from another site (not likely if they are truly a competitor). Basically, this technique involves placing links to competitors’ sites on your site, so you can check the state of the link (whether or not it has been visited) once the page renders. Then, using AJAX, you can send the information back to your server without refreshing the page, and therefore not letting your visitors know that they have been spied on.

This is one of those questionable practices that I personally don’t agree with and has elicited some strong responses from the user community, but is nevertheless interesting. Check out the full article for more info and be sure to leave a comment to let me know how you feel about this technique.

Update: Seems that mashable.com had a post about Spyjax as well. One of its readers suggested the Stanford SafeHistory extension to help protect yourself. Honestly, I’m not too concerned if someone detects which sites I’ve been to; it’s more a matter of ethics than a security concern from my point of view. However, if you are truly concerned, you might want to check it out.