Its weird that nobody mentioned Disconnect[1], which is an open source alternative to Ghostery. I've used it in the past, but shifted back to ghostery because it was buggy.
You should try the new Disconnect (Disconnect 2) which has a lot more features than Ghostery and is even rated higher by users than Ghostery is. We just launched Safari and Opera versions today (and are also available on Chrome and Firefox).
One criticism: It's not clear from the popup what the numbers mean. Are they counting scripts loaded, or scripts blocked? The same for the colouring. Are coloured icons blocked, and greyed ones allowed through, or vice-versa? And of course the tickboxes.
The numbers indicate requests (as in HTTP requests) attempted by the tracking companies. Green (or checked) indicates the requests were blocked. Gray (or unchecked) indicates they were allowed.
We'll beef up the help doc (https://disconnect.me/d2/help) to clarify.
Some pages I visit show 100+ requests but when I enter the add-on it only shows 2 advertising attempts and maybe 1 analytics request. Where do these other hundred requests come from and were they effectively blocked from communicating with its third-party provider?
Disconnect 2 basically replaces HTTPS Everywhere, which I find nice.
The number of requests in the dropdown menu should add up to the number of requests in the toolbar counter (we do group requests by company, which Ghostery doesn't do, so you will see less rows in Disconnect's UI if that's what you mean). Do you have a site where the two aren't equal?
Also, does "Wi-fi security" conflict with HTTPS Everywhere? The features seem to be analogous.
edit: Apparently it is free. Your website is incredible confusing and misleading. I read through it, saw the "Pay what you want" bit. Entered 0$ but nothing happened, no new button or something. So I assumed it was not available for free. I also did not see what browsers were supported.
I only found out that it works for Firefox on Github. That is also where I saw the GPL. And then I got curious what the "Get Disconnect" button might have done so I returned and clicked. And to my surprise it gave me an extension installation prompt...
The UI of the extension is completely opaque to me. What is "secure Wi-Fi"? I am not using Wi-Fi. What means "secure search"? No mouseover tips and https://disconnect.me/d2/help helps me nothing. I am not even sure what the things are that page talks about.
What are the Facebook, Google+ and Twitter counters/buttons for? I am not using those sites and I thought your extension would block their tracking. Why does it reload the current page if I click on those buttons?
I loaded a random page. There is a 8 on the DM icon but if I extend the dropdown it just shows 1 Analytics item. In the list that item has a ticked checkmark. Does that mean it is allowed? I do not want that tracker allowed. I thought you blocked automatically?
Please consider having a feature stop and work on the UI next. Right now I could not recommend this to my most technically versed friends because I am not understanding it myself.
Also, Disconnect has very confusing interface. There is content section with number which constantly counting allowed requests to trackers as I understood. Why? I installed this plugin to be not tracked or load any third-parties scripts. I was very excited about new (for me) Disconnect plugin, but not now. Can't recommend as well.