Firefox/Chrome/IE/Safari: previously mentioned Do Not Track Plus has picked up a new name and a major update: The extension is now called DoNotTracKMe. It has a streamlined UI that makes it easier to control, and it still protects you from prying eyes and ad-tracking cookies.
The new DoNotTrackMe is more than just a makeover and new name though. The app lives in the toolbar now, so you can turn it on and off if it breaks a site you're browsing, It also actively shows you what is being blocked on any given page. You can even dive into the details to see exactly what data the website is trying to obtain and choose what you're OK with and what you want blocked.
The extension also keeps social buttons and plugins active instead of removing them the way other extensions do. However, DoNotTrackMe blocks those social plugins from working until you click on them.
If you're already familiar with apps like Ghostery and Disconnect, you already know how the app works. DoNotTrackMe is free and available for all supported browsers right from the developer's website at the link below.