An anonymous reader writes: The Guardian newspaper have teamed up with Mozilla to research the monitoring of online behaviour through cookies and other web trackers. After downloading the Collusion add-on for Firefox, you can generate a visual representation of all the cookies that have been downloaded which are linked to the sites you have visited. This shows quite an interesting picture. The Guardian then want the data from Collusion to be uploaded to their site after which they say "we can build up a picture of this unseen world. When we've found the biggest players, we'll start tracking them back – finding out what data are they monitoring, and why."