Nice! Up until now I've been writing small GreaseMonkey plugins to handle this. Added your list. Expect the occasional pull request. :)
[edit] First pull request sent.
first pull request merged. look forward to many more :)
I like the idea, but won't this prevent you from accepting cookies if the site has actually bothered to ask permission before adding them?
You're right to have that concern, I won't block a site if it's doing that but practically it's not an issue. I've yet to encounter one that requires opt-in before setting cookies.