I’ve been searching for a while for a way to extract cookies from Firefox 3.x in order to use them with stuff like wget and Perl’s libwwwperl, which I have been using for a bunch of scripting. Firefox 3.x uses sqlite to store cookies, whereas apps which let you load cookies files are looking for IE or Netscape formatted ones. The latter were used up to Firefox 2, but I’ve had trouble keeping FF2 and 3 happy on the same machine… And going back to FF2 feels really painful without the magical search bar of awesomeness.
There’s now a beta extension up to save your FF3 cookies to the right format, which makes me a very happy camper! It’s on the official addons.mozilla.org site but you need to sign in to the site to download it here as it’s still experimental. Super useful though!