Nice idea...unfortunately when you click on the correct spelling option and return to the page you need to remember where the mistake was AND the correct spelling option(s)...? in other words, (unlike the E mail spell checker) the correction(s) are not automated... ::) ::) ???
Works here, click 'Change' button and it corrects spelling in your post.
I use Firefox, and that highlights spelling errors as you type anyway, but my spelling is very good anyway, so rarely need to use it! ::)