This is the logic that makes everyone move their workflow into emacs. A lot of what we do is text editing, so having a good text editor everywhere makes sense. Some programs like mutt can also drop in to your editor of choice when composing an email. Imagine if we all had vim for typing up these HN comments. I'd like something like this to be more feasible. Maybe there could be a standard for forums that gives you vim editing in the same way many give you markdown. It could also be cool to support org-mode syntax.
Imagine if programs knew how to interact with one another and could plumb data between them instead of everything living in one monolithic application.
There are browser extensions that offer this. E.g. the excellent Tridactyl for Firefox lets you pop up a gVim window for any text box if you press Ctrl+i.
This has been possible for years with Vimperator and then Pentadactyl. Unfortunately it's awkward and can't take advantage of text fields with real time JavaScript processing (e.g.: Gmail, Markdown preview).
There is surfingkeys for chrome. You press `shift+I` to go into into insert mode.