If you use the NoScript addon for Firefox, or simply apply iptables or a similar way to block specific domains, you may find this list of advertising, data pharming, and tracking domains that you should ban as a useful resource.
BLOCK THESE:
addthis.com adnxs.com adobetag.com adroll.com adshost1.com adzerk.net adziff.com axf8.net bluekai.com bridgetrack.com chartbeat.com coremetrics.com csdata1.com doubleclick.net ensighten.com exchangesolutions.com facebook.net fbcdn.net flightstats.com followgram.me gigya.com google-analytics.com googleadservices.com googlesyndication.com googletagmanager.com googletagservices.com gsimedia.net invodo.com macromedia.com medleyads.com monetate.net msecnd.net netshelter.net omtrdc.net phncdn.com richrelevance.com sellpoint.net taboolasyndication.com trafficjunky.net tru.am twitter.com veinteractive.com verisign.com yieldmo.com