The goal is to offer you a new functionality within the useful Firebug. It will make easier to deal with cookies without having to open a new panel.
That new column added by Firecookie will feature detailed information about the cookies in your browser such as name, value, date, domain, size, path and expiration date. Everything at a glance.
If you want to locate a certain cokie, just use the search box. Finally, you'l be able to create new cookies and manage the ones in your system.
It requires Firebug.