Update 02-2015: things change, blogposts get out of date and indeed A2A is not owned by Lockerz any more.
AddToAny, one of the most popular sharing-widgets around, has had 3rd party tracking by Media6degrees for quite some time already. I wasn’t too happy about that, but it did have the no_3p option to disable this “functionality”. Half a year ago however AddToAny was acquired by Lockerz.com and it now includes tracking by Lockerz.com which cannot be turned off and does not check for navigator.doNotTrack either.
I’ve contacted the developer (Pat’s a swell guy, really) and he answered he would look into honoring the DoNotTrack header, which he wrote he’d love to include in Q1 somewhere. In the mean time, if you have AddToAny on your site, you can already hide the Lockerz “Earn” tab. And if you’re on WordPress, you could install (or upgrade) WP DoNotTrack, which I’ve updated to stop the Lockerz tracking (make sure lockerz.com is your blacklist).
If there’s a Drupalista out there that uses AddToAny and would like to stop Lockerz tracking; I’d be happy to co-author a Drupal DoNotTrack module, do get in touch!