I use Ghostery, (http://www.ghostery.com) but have found than some sites just don’t work properly, unless you ‘unblock’ certain trackers..     Examples are Disqus (http://disqus.com) for some of the ‘outsourced’ discussion forums on news sites, and one closer to home is Adobe Typekit, which is used to provide a source of fonts for many of the WordPress Themes..    So, if you are finding that your Typekit font changes just aren’t working, then make sure to ‘unblock’ the Typekit by Adobe tracker in Ghostery..    And..  If any visitor to your site has all the Ghostery trackers blocked, then they will only see non-TypeKit fonts, thus spoiling all your carefully crafted design..     Personally, I will be switching to other font sources in the future..