And people say I'm paranoid for having cookies disabled by default, and only enabling them on-demand - and after use they are cleared again.
Yes, it's a pain having to type in your password every time you make a forum post etc.- but it's worth it imo. FF extensions like cookiesafe easily let you do this at the click of a mouse.
It's probably also an even better idea to have a separate, sandboxed browser environment to do your online banking on. (Or even use a vm just for the purpose).