Solving the "losing your work on forum posts" issue at the browser level?

I'm sure many of us have had the wonderful experience of spending some time on a web forum post, blog comment, message on a social site, email from webmail client, etc. -- in short, something typed into a browser text box -- and losing it due to some server or connection issue.  Of course, a solution is to always type any long text you're composing into a separate text editor window, and copy + paste, but for some reason no matter how many times I'm burned by not doing this, and tell myself to be sure to do it next time, I still keep forgetting to do it.    I suspect many others are in the same boat.

It seems to me that rather than relying on every web developer to account for this in their software design, this could be dealt with by the web browser by incorporating more editor-like features into their text boxes.  For example after noticing that you'd typed a certain amount into a textbox, the browser would automatically save it to a file (perhaps it would also display its name for the file in the status bar, and an inobtrusive icon similar to Word's autocorrect/IE8's Accelerator icons would appear allowing you to change the name) which would then show up in a "Composition Manager" screen allowing you to browse and search for previous text entries.  Does anyone know of browsers or plugins with features like this?  I know of a Firefox plugin called "It's All Text" which lets you open a separate text editor window with one click on an icon that appears in textboxes, but of course that's not quite the same.