Vote: How to Detect the Social Sites Your Visitors Use
azarask.in
azarask.in
Also, it would probably be possible to recurse on a site and figure out what pages they are visiting. For example, suppose a top-level detect shows that I visit reddit.com, the system could then load up a reddit specific page and discover that I also visit reddit.com/r/funny. I would imagine that for some sites that could be very revealing.
I didn't realize that works.
That said, I've gotten to the front page of delicious and reddit without stupid tricks like this. I just wrote an article that people liked. (What a concept.) I don't have ads either.
I'm not positive on the overhead for this. Loading a couple of links in an iframe shouldn't be too expensive.
But if it were a problem you could easily create a solution to store these settings in a cookie, so the iframe would only be loaded once.
I heard about this technique a while back in a presentation about javascript malware: http://www.spydynamics.com/spilabs/education/presentations/J...
.. there's a whole section on stealing browser history and how to figure out a user's search history.