Google search and other search engines and websites seem to ignore Mozilla’s ‘Do-Not-Track’-header and add tracking functions to their search results and external links anyway. This add-on shows tracking-free links or optionally replaces the results with those links.
The websites supported thus far include: Google, YouTube, Yahoo!, Bing and Facebook.
Here is a little more about the add-on from the developers:
This add-on does not — and cannot — recognize every mechanism companies use to track user behavior! In fact, this will be probably a losing battle. With every redesign of a website, tracking mechanisms change, and this add-on will definitely become obsolete rather sooner than later. For our most used websites, We will try to keep this add-on as up-to-date as possible, but some others may fall through the cracks…
For this reason I suggest you don’t use this add-on on its own. There are a lot of privacy and security add-ons out there, with RequestPolicy and FlashBlock being my favorites. I would recommend you to use these to together with this add-on. But there’s also NoScript, which I personally don’t use, but it comes highly recommended.
Want to pick up this add-on? You can find Google Privacy at the Firefox Add-ons website.