Not only that, they can read any "cached" forms or passwords in your browser.

The password manager we recommend will prove that. It's called LastPass. When you install it, it asks if you'd like it to import and encrypt stored forms and passwords from your browser. If you say yes it will read all of them on every installed browser on your machine. Chrome, Firefox, Safari or IE. Doesn't matter. It's another program running on your machine that has the same rights as you do (it runs in the security context of the logged-in user).

Perhaps that will also make you think twice about having your browser remember your forms data or cache your passwords. (Edit -- meant "you" in the general sense. Not you in particular, Jon).