Firefox (Vista):
%APPDATA%\Roaming\Mozilla\Firefox\Profiles\gs2lr6r5.default
files with the word cookies in them, obviously. Firefox stores cookies in a sqllite database, at least, that's what I gather from the file extensions.
Or, more directly, in browser:
Tools > Options > Privacy > History: Firefox will: "Use custom settings for history" click "show cookies" to see ALL the cookies. including those from facebook.
Internet explorer:
direct view (Vista):
start-> Run: "%APPDATA%\Local\Microsoft\Windows\Temporary Internet Files"
or, in browser... well, sorta
IE7: Tools->Internet Options, General tab, in the browsing History section, click the Settings button. Click "view files" in the displayed dialog.
Internet Explorer 6 Cookies (KB article)
http://support.microsoft.com/kb/283185Lastly, ALL cookies are stored together; there is no special place for facebook cookies. If your not seeing facebook cookies with the other cookies in the locations above, then there simply aren't any.
Cookies have no magical powers. they are text files. topics about cookies often turn into the same sort of arguments that a topic about text files might*- one about whether Carriage return, Line-feed, or Carriage Return + Line Feed are the best text file format. It doesn't matter that nobody cares, it matters that there is something to argue about, and people are too damned proud to not voice their opinion, even though EVERYBODY knows that carriage return+ Line-feed is the best, I mean- thats two characters where the others only have 1.
* Normally this only happens if the discussion gets to around 10 or 15 pages