It's frustrating how the Google Toolbar solved this problem perfectly 10 years ago, then stopped working consistently.
I should never have to type in a password, credit card number, or address if I don't want to... yet nobody except a few proprietary browser plugin vendors treats this as a problem worth solving.
Opera supports this out of the box since 2003 (according to the version history). It's not perfect in my opinion, but I'd say it's not because the web is broken.
One problem, though, is that banks and merchants tend to flag the credit-card field as "Never autocomplete, even if the user has explicitly requested otherwise."
Any tool that actually solves the problem, at least from my perspective, is going to have to give me the option to ignore whatever security conventions are built into the standard(s).
I think it is reasonable to demand not to autocomplete on the server side. Do they really demand not to autocomplete on the client side? In x-autocompletetype case, all CC information stays in the browser, only thing server does is to mark "this is CC field".
I should never have to type in a password, credit card number, or address if I don't want to... yet nobody except a few proprietary browser plugin vendors treats this as a problem worth solving.