Keeve:
For example, there are a gazillion websites where I have to type in my email address. But as far as I know, neither Firefox nor Internet Explorer have a feature where I can type something like “PW” and it will know to automatically replace it with my password. I have to either type it in myself, or paste it from somewhere, and a standard “multiple clipboard” WOULD be good for that (except I don’t see how it would be better than blah blah blah, for which see my previous post).
If you are referring to logins and passwords for known sites, you can opt to remember these in the Firefox security options.
I totally agree with the OP. It seems to be a no-brainer. Also I would like to see more flexible searches with pattern matching and the ability to open multiple search result viewports from the same base.