Icon not showing? Rated 3 out of 5 stars
I'll second gentmatt's comment. I use NoScript set to global deny, and have Collusion running, apparently almost correctly.
The only bug which afflicts my installation is that Collusion's icon might not show in the Add-on Bar. If, when starting Firefox, there is no Collusion icon in the Add-on Bar, then go to about:addons, find Collusion, click on the 'Disable' button, pause, then click on the 'Enable' button. Now the Collusion icon is visible? It works for my Firefox.
"Before that: Collusion showed pged that were linked to my computer, even those that were not loaded. Even the cookies of these pages were deleted but Collusion continued to show all the pages."
By all means delete any cookie that takes your fancy; however, Collusion is not reporting on what is in your cookie cache, it reports on what it 'saw' go in to the cache. Deleting a cookie does not change that detail.
"edit2: those looking for an add-on to block trackers. Check out DNT+ on http://www.abine.com/dntdetail.php"
Surely, the Do Not Track option merely asks trackers to be nice and pass over an opportunity to track?
Use Adblock Plus + filter list and leave the tracking oddments on the trackers' servers? No downloading; no logging of download destination; no tracking? Um. Cookies help with tracking; especially third party cookies.