But you may think that's intrusive, which is why you may want to use RequestPolicy. (Note: This add-on is probably not suitable for you if you're not comfortable digging under the hood of a browser and making changes.) If other browsers have similar add-ons, I haven't heard of them.

Lastly, let's go over the basic defenses you can use against the most common and less sophisticated tracking techniques.

All of the major browsers have some built-in defenses. The first is called private browsing, which stops your browser from making note of where you've been in its history file. That's worth doing if you're visiting sites that you don't want other users of that computer to know you've visited. It's very easy to turn on private browsing; in Firefox for example, simply click the "Firefox" button and select private browsing. IE 9 has an option called "inPrivate" browsing you can find on the tools tab and Chrome has incognito mode.

But private browsing isn't necessarily all that private. In addition to the super cookie issue, some of the extensions you might add to those browsers can reduce their effectiveness. Still, it's certainly worth using private browsing modes if you're concerned about tracking. You can also check a box that says something like "tell Web sites I don't want to be tracked", and as you'd expect, some Web sites will honor that and others won't.

Finally, drill down. Each of the three major browsers has quite a few settings involving privacy, and it's worth a few extra clicks to check them out.