You know (forgot to say this last night), you can use the Web Dev add-on to disable all cookies, too, but as far as I know, it's not a persistent setting, so every time you restart Firefox, you have to check off "disable cookies" again. Which is why I almost never bother with that feature.

Right now I have Firefox set to block all third-party cookies, and NoScript is preventing (I think) any cookies from being set when I use it to block scripts globally, but sometimes, on certain wireless networks, I have to disable NoScript or the networks are unusable (because the IT who runs them tracks you through certain tracking websites, which ugh, I hate). So I'm thinking, since I have to disable NoScript so often, I might as well re-install Ghostery. :)