Ghostery is to trackers what ad-blocking programs are to annoying ads. They smite them. Actually, Ghostery is programmable, so you can set your preferences. Certain trackers are required for the site to function properly. You can green light those, but have it block all the rest.
The program runs quietly in the background. The only things I ever hear from it (meaning a pop-up message) is when it discovers new trackers and offers me the chance to review them, if I'd like to. There's a tiny blue ghost icon on my tool bar, and a little purple circle that pops up as a site loads. It's almost fun to see just how many trackers some sites are running on their users. Six to ten isn't horrible, but my cell phone company had 24, and a news/commentary site had 47. Forty-seven different trackers. And they were blocked. I recommend this program to anyone who spends any real time online.