A Clever Hack

Once in a while you see things and think "Seems so simple, Why didn't I think of that?". This Hack by Aza Raskin belongs to that Category. He created a simple and smart way to read user browser history. In the example here, Aza is maintaining an array all the social networking sites he is aware of and checking which of those site the user has visited. How can he do that? By checking the color of link referring the Site. In his own words:

By using a cute information leak introduced by CSS. The browser colors visited links differently than non-visited links. All you have to do is load up a whole bunch of URLs for the most popular social bookmarking sites in an iframe and see which of those links are purple and which are blue. It’s not perfect (which, from a privacy perspective, is at least a little comforting) but it does get you 80% of the way there. The best/worst part is that this information leak probably won’t be plugged because it’s a fundamental feature of the browser.