Anyway, I think this is something, and use it, Better Privacy, both in Firefox and Seamonkey.
Better Privacy serves to protect against not deletable longterm cookies, a new generation of 'Super-Cookie', which silently conquered the internet. This new cookie generation offers unlimited user tracking to industry and market research. Concerning privacy Flash- and DOM Storage objects are most critical.
This addon was made to make users aware of those hidden, never expiring objects and to offer an easy way to get rid of them - since browsers are unable to do that for you.
Flash-cookies (Local Shared Objects, LSO) are pieces of information placed on your computer by a Flash plugin. Those Super-Cookies are placed in central system folders and so protected from deletion. They are frequently used like standard browser cookies. Although their thread potential is much higher as of conventional cookies, only few users began to take notice of them. It is of frequent occurrence that -after a time- hundreds of those Flash-cookies reside in special folders. And they won't be deleted - never.
(Another reason I don't worry too too much when I'm on social networking sites LOL )