Give the "Cookie Monster" extension a try. You can browse with a default "no-accept-cookies" policy, but at browse time decide to (based upon the domains of the cookies):
1) temporarily allow cookies from some domains;
2) permanently allow cookies from some domains.
Gradually you can build up a whitelist of just only those sites where you will allow cookies, even while blocking their own advertisers/trackers from setting cookies, while keeping everything else off.
did you read my comment? i'm using cookie monster.
blocking by default and only allowing the current domain breaks quite a few sites that refuse to work without an active session cookie. some break subtly and some throw you into a redirection loop. that is why i accept all by default, but firefox marks them as session cookies so they don't survive across browsing sessions, and using cookie monster i whitelist a few domains.
1) temporarily allow cookies from some domains; 2) permanently allow cookies from some domains.
Gradually you can build up a whitelist of just only those sites where you will allow cookies, even while blocking their own advertisers/trackers from setting cookies, while keeping everything else off.