My Safari 3 browser has a spell checker built into it, so that when I type a post or reply in Answerbank, I get squiggly red lines under suspect words.
It still does not me making far too frequent typos though.
Hopefully, this won't be included as some of the questions in the quiz section would be impossible to post, as they include initial letters and are often not full words.
Although I can spell very well, for some reason on AB I look back and find loads of errors when I type answers. I have just put the google spellcheck on my toolbar.