Interesting...one solution from the perspective of the tracker might be a system that assigns different weights to different types of information, with things like fonts and browser plugins given less ranking than things like OS, browser type, and time zone, which probably change much less frequently. You might not be able to get 100% unique tracking, but if you could guess that there was a 99% chance that it was the same person, doing things like behavioral advertising would probably still be worth it.<p>The interesting application of things like this and the visited link color hack is to use them in Europe, where apparently you have to get users to approve a cookie every time? This might be a good way to skirt the issue for a lot of sites that don't need a guarantee that it's the same person.