Self-Destructing Cookies automatically removes cookies when they are no longer used by open browser tabs. With the cookies, lingering sessions, as well as information used to spy on you, will be expunged. Websites will only be permitted to identify you while you actually use them and can not stalk you across the entire web. This is the closest you will get to cookieless browsing without breaking every second site or tedious micromanaging.... More Info »
Tracking cookies will be detected and removed immediately. They are identified purely by their behaviour - no need for a blacklist that needs to be kept up to-date. Self-Destructing Cookies also has LocalStorage support and will treat it just like your cookie jar. Defend yourself against ETag tracking and other cache-based black-hat techniques by configuring Self-Destructing Cookies to automatically clean your cache every time you are not actively using the browser. For the first time ever, this provides a realistic chance of beating zombie-/evercookies without sacrificing usability. See the zombie-cookie FAQ entry for details. Self-Destructing Cookies can also help protect against CSRF attacks by ending your sessions as soon as possible.
This add-on complements blacklist-based solutions such as Adblock and Ghostery very well. You can whitelist sites whose cookies and LocalStorage you would like to keep without an active tab in the Firefox cookie exception list, which can also be conveniently accessed from the add-on's preferences, or an icon in the Add-on Bar.