Here is a screeshot of my collusion graph after about 2 hrs browsing. It wasn't looking too bad until I followed a link to ReadWriteWeb which made it double in size.

This is somewhat disturbing. I figured that FB/Twitter/Google would be tracking me, but one visit to RWW and suddenly a very large number of dots appeared and connections between sites.

RWW is the one in the lower middle, with a total of 23 connections. It also brought along an extra 8 or so sites that weren't there before.