Courtesy of Ghostery-
Skipping the big players like Google & Facebook, *two* news articles on the net produced the following trackers:
List 1
AddThis
Clip Syndicate
LiveRail
Outbrain
Quantcast
Quogo AdSonar
Unica
Vibrant Ads
List2
Audience Science
BlueKai
MSN Ads
Scorecard Reseach Beacon
Tynt Insight
Who ARE these people?!
That's the trench view of people selling you as a product.