Re: Yes! Someone's remembered TrackMeNot
The problem is its 'behaviour' is easily identified and, furthermore, it can also be (mis)detected as being of malicious intent (e.g. DoS / part of a DDoS attack).
It's also a pain to set up - you have to add all your regular sites to the mix and, if they don't show you how they formulate their query strings like a search engine does in the URL/URI box, you can't (or at least not easily).
It really needs to learn the user's behaviour and add regular sites automatically - but that wouldn't solve the search query formulation problem and would, furthermore, add an element of "Do I trust this addon that much?"